I can't really think if any reason why a mod would work in WOTLK and not 3.0, they are identical as far as mods are concerned. There are tons and tons and tons of mods that haven't been updated for 3.0 yet, but I can confirm Pitbull, Bartender4, Chatter, Auctioneer, Chinchilla are all working for me. I dumped Cartographer and instead have Mapster, Gathermate, TomTom, Lightheaded - although tbh they are not as nice as Cart

Haven't found a good buff mod yet, ElkBuffBar seems a bit messed up and I don't like Buffalo at all.