A handful of WAN optimization and application acceleration vendors recently announced financial results for the last three months of 2008, and it's clear the economy is taking a toll. Still there are some bright spots to share, including customer growth. Here are the details from Riverbed, F5, Citrix, Akamai and Radware:

Riverbed: In its fourth quarter ended Dec. 31, Riverbed reported revenue of $92.2 million, a gain of 21% over the prior year’s Q4. Net income for the quarter was $23.3 million, compared to net income of $4.8 million in the fourth quarter of 2007. (The big jump in Q4 income is due to the release of $28.7 million related to the company’s deferred tax asset valuation allowance, Riverbed says.) Revenues for the full year came in at $333.3 million, a 41% increase from $236.4 million in 2007. Net income for the full year came in at $10.6 million, a 28% drop compared to net income of $14.8 million in 2007. On the upbeat side, Riverbed added 2,000 customers in 2008.

F5 Networks: F5 announced revenue of $165.6 million for its first quarter of fiscal 2009 (ended Dec. 31), up 7.4% from $154.2 million in the first quarter of fiscal 2008. Net income for the first quarter came in at $21.4 million, compared to $17.8 million reported in the year-ago quarter. Revenue fell short of expectations due to a sudden fall-off in North American sales during the last week of December, according to F5’s president and CEO John McAdam. "Our current analysis indicates that most of these deals were pushed into our second or third quarter of 2009 due to budget constraints. However, several were postponed indefinitely as customers evaluate their expense budgets in light of the continued recession,” McAdam said in a statement.

Citrix Systems: Citrix announced a restructuring program along with financial results for its fourth quarter and fiscal year ended Dec. 31. In the fourth quarter, Citrix reported revenue of $416 million, a 4% gain compared to $400 million in the year-ago quarter. For the full year, Citrix reported revenue of $1.58 billion, up 14% over 2007’s $1.39 billion revenue. On the profit side, Citrix reported $60 million in net income for the fourth quarter, compared to $63 million in the year-ago quarter. Annual net income for 2008 came in at $178 million, a 17% drop compared to $214 million in 2007. Citrix’s restructuring program -- which includes facilities consolidation and a 10% workforce reduction -- is aimed at reducing the company’s annual operating expenses by $50 million.

Ann Bednarz is associate news editor at Network World.