I was also pleased to find my CSS page validates, though it does generate some warnings as well.
It should be noted that the RSS standard is not as well established as either the CSS or HTML standards. For more about this, start with Ben’s call to action, and follow the links from there.
I’ve a ways to go to get the rest of the site to validate, but this is progress! (You can test the validation yourself; look for the buttons on the bottom of the left nav bar.)
And for those going, “huh? what’s validation and why does it matter?”, consider this: if web pages are compliant, then any compliant browser may view them correctly. If they are non-standard, then only some people would be able to view the site correctly. This is less important today, but as web pages are started to be viewed on phones and PDAs, etc. it is critical that they be written so that they display well in any standards-based browser.
That’s way over-simplified for those of us who do this for a living, but it hopefully gets the main point across to others who are just becoming aware of the issues of compliance (to say nothing of accessibility!).