I've been using PNG for quite a while. But when i comes to transparency, I've stuck with GIF. Mainly because of IE/Win's lack of PNG transparency support.
Zeldman has a post on the topic. It includes a link to a petition you should sign.
Good: he is very sincere and serious about Web standards.
Bad: OH GOD DYING OF BOREDOM IN THIS HELL OF NATTERING ABOUT CSS AAAAAAAAA.
Good: he's an actual designer.
Bad: his design sense seems firmly planted in album cover art from 1998 -- even down to his book cover, which is such a fashion and design catastrophe I don't know where to start.
