I, like many people on the Internets, was ecstatic at the announcements of IMAP for Gmail and the blogosphere-dubbed "Gmail 2.0". I'm all for a faster Gmail experience, not to mention an implementation of the mail retrieval protocol that was developed at my alma mater. However, my enthusiasm waned in two parts, when I actually tried out these features.
When IMAP was finally enabled on my account, I opened up claws-mail and configured it to use Gmail as its mail source. When it did the mail sync operation, I noticed that it didn't populate the virtual "label" folders properly. By that point, I gave up and did something else. I learned later during my blog reading that Gentoo's flameeyes had the same problem. If you look at the comments, you'll see that Claws-Mails's developers have acknowledged the problem as Google's fault. As a(n annoyed) developer, I would agree with their assessment. As a pragmatic developer, however, I agree with flameeyes's assessment: The Claws-Mails developers should follow Postel's Law.
I do realize that these features are relatively new, but you'd think user/unit testing would catch these things.