There is a thread at WebmasterWorld named Google showing my RSS page, not main page. This person describes a case where Google is listing his rss URL to a podcast feed, as the main listing in the results page for his prime keywords. Now, the last thing he wants or his user wants is to be defaulted to an RSS feed, that is no good for anyway. What can he do?
Well he can detect the referrers and then serve up a redirect from the SERPs to his homepage. But that might not be too safe.
He can try contacting Google and tell them to fix it, but that may take a long time.
He can try building more links to the homepage URL, but again, that may not work or may take more time.
He can wait for the big daddy update to propagate and hopefully fix the issue, again timing...
Or he can use financialhost's idea in the thread to use "XSL to turn your xml into a normal looking webpage."
Forum discussion at WebmasterWorld.