iChat AV: WHICH TYPES OF CHATS ARE THEY UP FOR?

If you're wondering if someone in your Buddy List can do a particular type of chat with you, just click on their name in your Buddy List, then press Command-I to bring up their iChat Info dialog. From the Show pop-up menu at the top of the window, choose their buddy name, and at the bottom you'll see a header called "Capabilities," followed by a list of all the types of chats they're capable of participating in, so you'll know if they're "up" for a particular kind of chat.