Oracle has shown a strong commitment to support Linux.
I've been working with Oracle on Linux for the last 4 years, started with benchmarks between our old Unix systems and the new 4 cpu's Linux's boxes; since then I saw the install base increasing in our big customers from a couple of test Linux boxes to hundreds of them serving both production, development and test environments.
In terms of stability, scalability and performance our experience with Linux has been excellent.
Today you can download Enterprise Linux free of cost directly from Oracle, and get support for your installation from Oracle as well. This doubtless will mean another push for database management in all the spectrum of available hardware, from the cheapest to the more sofisticated, that can run Linux.
You can find a wealth of information about Oracle on Linux at OTN's Linux Technology Center.