With the announcement of $1.3B in damages awarded to Oracle in the lawsuit against SAP , Oracle has made abundantly clear that they intend to do everything they can to lock customers in to their expensive and highly profitable maintenance and support fees. Of course TomorrowNow made it ridiculously easy for Oracle by stealing Oracle's IP, but Oracle seems likely to go after other third-party support providers as well.
All this litigation has effectively crystallized one of the major reasons for companies to use open source software. Unlike proprietary software, support for open source software is a competitive market. For almost any major open source project, there are multiple vendors that companies can choose for support. In addition, if they have the internal expertise, companies can even choose to self-support. Unlike the Oracle scenario, the source code and documentation for open source projects is freely available, so all open source support vendors have access to the key information needed to support users.
Because there is choice in the world of open source support, customers are in the driver's seat. Instead of having prices and terms dictated to them and changed at the whim of a proprietary vendor, open source users can pick and choose the offering that meets their needs and their budget. In general, the support costs for open source software are much lower than those of proprietary software, because open source support vendors have figured out how to provide high quality support more efficiently.
While open source vendors can and do raise prices, as was seen recently with Oracle raising prices on MySQL support , companies can choose to switch open source support vendors or even switch to a fork of the same project. Companies that use open source are able to keep their options open - avoiding vendor lock-in and the accompanying costs.
Disclosure: I work for OpenLogic, a provider of support for open source software.