Tried to join the project running AMD Phenom II 965, 8Gig DDR3, Multiple Raids on Linux and got:

Sun 13 Nov 2011 01:16:32 AM CST BURP Message from server: SunflowerBlender _("is not available for") Linux running on an AMD x86_64 or Intel EM64T CPU.

I see Linux is supposed to be supported - is it something with my system?

Nothing wrong with it.
The message appears from time to time, even if there is everything okay.
There are currently only two sessions running which need more than 8 GB of RAM, even session 1279 needs 8,7 GB.

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Life is Science, and Science rules. To the universe and beyond
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Then the question becomes are there work units available that are compatible with my system? I have not received any work.

You just have to wait.
If you look at the server-status there are three normal Blender-sessions to accept which don't need much RAM.
And there will be for sure other sessions with less than 8 GB.

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Life is Science, and Science rules. To the universe and beyond
Proud member of BOINC@Heidelberg
My BOINC-Stats

Currently the Linux clients receive the "difficult" work in the Sunflower event - that is the experimental physics-based workunits. The last run of these workunits didn't turn out well (the physics was wrong). For a while now there hasn't been any new work for Linux. When the physics issue has been sorted out there will be new Sunflower workunits for Linux as well.

For the normal work queue (where both Linux and Windows shares the workunits) there simply hasn't been any work accepted recently.