I am using a gmail account in Mail (via IMAP) on Lion, and it works well. My dad just set up a gmail account and he is on SnowLeopard. Does a gmail account work correctly in Mail (also via IMAP) on SnowLeopard? If not, what are the issues?
I'm assuming you are configuring Gmail for IMAP and not POP. Google has posted extensive instructions on optimizing Gmail with Apple Mail. You should check them out.
There is also this excellent article from MacWorld, March 14, 2011: How to make Gmail work well with [Apple] Mail.