Attendees headed to this week's LinuxWorld Conference & Expo in San Francisco will be looking for application, desktop and middleware support instead of questioning the operating system's viability.Attendees headed to this week's\u00a0LinuxWorld Conference & Expo\u00a0in San Francisco will be looking for application, desktop and middleware support instead of questioning the operating system's viability.Linux\u00a0no longer raises red flags, says David Cook, chairman of InsiteOne, a Wallingford, Conn., company that provides digital-image storage and archiving solutions to the medical community. "Today when we talk to large clients it's generally a plus that we developed our application on the Linux platform."Also: Linux adoption continues as SCO battle wages onUsers and analysts say the maturation of Linux is giving LinuxWorld the feel of a mainstream show."If you look at the agenda you see desktop bubbling up higher, you see things like operating in a mixed environment," says Pierre Fricke, an analyst at D.H. Brown Associates. "We're now talking about plugging Linux into the enterprise as opposed to [simply using it in] departmental-level or simple infrastructure roles. We're talking about mainline enterprise issues."Analysts say desktop Linux will be a key focus at the show, with HP and Sun announcing Linux-based thin clients. Fricke also expects to hear about open source middleware technologies."Things are moving up the stack," he says. "Linux is not an enterprise system without things like databases and [Java 2 Platform Enterprise Edition] application servers. They have had those in WebSphere and DB2 and Oracle and WebLogic, but now you've got open source players getting more serious, and that's going to make things interesting."Red Hat is expected to release its first Java application server at the conference, following through with plans it announced last year to broaden its business beyond the core operating system. Computer Associates is expected to join the open source community, reviving its Ingres database with Version r3, which the company is scheduled to announce as a Linux open source project.Show organizer IDG World Expo, a sister company of Network World, expects about 10,000 people to attend the conference, which has attracted more business buyers in recent years to complement the traditional techie showgoers of the past. The additional 55 exhibitors this year will bring the tally to more than 200 companies.People are saying, "OK, we've heard all the stuff about the city of Munich [moving from Windows to Linux], we've heard about Windows' patch management ills, we've heard about the expensive Windows and Office licenses, now tell us more about Linux," says Laura DiDio, senior analyst at The Yankee Group. "If we're going to switch to Linux, what do we need to get up and running? What's available now, and if it's not available now, when will it be available and how much will it cost? What about integration and interoperability with other environments?"For InsiteOne, Linux has grown up alongside its business. The company deployed the nascent operating system internally when it launched its first product in 1999."Our own growth has been a microcosm of the Linux market," Cook says. "As our business has grown we've run into scalability issues, and fortunately Linux has grown and faced some of the same issues and solved them at the same time."The Linux kernel once fettered by limited support for symmetric multiprocessor systems, now supports up to 64 processors with the release last year of Version 2.6. That kernel also features support for distributed application environments, 64-bit computing and Intel's Hyperthreading technology, which lets a single processor perform as if it were two processors."If you look at the Linux 2.6 kernel, it is already more powerful than the majority of Linux users need," says Dan Kusnetzky, vice president of system software at IDC. "Linux 2.4 was good enough to do what most people were asking Linux to do. Moving to 2.6 creates a great deal of headroom, which will be good for future deployments."The major Linux distributors have not released updates based on the 2.6 kernel, although sources say Novell will announce the availability of SuSE Linux Enterprise Server 9, which runs on 2.6, at the show. Red Hat has said it will integrate the kernel into its next release later this year.Nevertheless, some Linux professionals already have the software running in production. Oregon State University in Corvallis uses custom-built 2.6 kernels based on Debian Linux to run its Open Source Labs site. The servers - Dell and HP boxes - recently were upgraded to the 2.6 kernel to help run the servers more smoothly; the boxes have dual Intel Xeon processors and 2G bytes of memory, and are connected to 4T bytes of storage."Since moving to the 2.6 kernel, our processor usage has been cut in half," says Scott Kveton, program director for the university's Open Source Lab. Kveton will speak at a LinuxWorld session on building high-performance servers with Linux.Show samplerA slew of companies plan to make announcements at this week\u2019s LinuxWorld.Vendor Expected show plans Computer AssociatesAnnouncing its Ingres r3 database as open source software running on Linux as of Sept. 30. DellDemonstrating PowerEdge servers with Intel\u2019s 32-\/64-bit technology.HPAiring pre-tested Linux hardware and software packages; supporting Linux on midrange and high-end Integrity servers; expanding Linux services and support team; introducing a Linux thin client, the HP Compaq t5515; and showcasing new ProLiant servers with Intel\u2019s 32-\/64-bit technology.IBMAnnouncing broader ISV support for Linux on its Power processor; unveiling new xSeries servers with Intel\u2019s 32-\/64-bit technology.Novell Unveiling SuSE Enterprise Server 9.0, which runs on the Linux 2.6 kernel and boasts better support for multiprocessor systems.Rackable SystemsDemonstrating Scale Out Server series, which can fit up to 184 CPUs in a typical 44U rack.Red HatExpected to release its first Java application server.SunAnnouncing that its Sun Ray thin clients will run on Red Hat Advanced Server 3.0 and SuSE Linux Enterprise Server 8 and that it will roll out the Sun Studio 9 integrated development environment for Linux on the desktop.VeritasAiring latest versions of its storage and clustering software, including Veritas Storage Foundation and Veritas Volume Replicator, are all certified on Red Hat Enterprise Linux.