Inside Mac OS X 10.7 Lion: iChat 6 adds Yahoo IM, account integration, web page sharing
New in iChat 6
In addition to Yahoo chat support, the new iChat 6 combines separate chat accounts and protocols into an integrated buddy list. By default, it also now coordinates logins across all your configured accounts to share the same status, although this option can be disabled so you can manually set a different status for each account you use (as shown below).
iChat Theater now supports a new type of shared document as well: live web pages. As with other types of shared documents, sharing a web page allows a user to present a controlled view of a web page to a user via an established video chat. The sending user can navigate around the page on their end, and the the receiving user sees a static view of the page being shown.
iChat vs FaceTime
Last year, Apple brought video chat to iPhone 4 under the name FaceTime, and later added support for both iPod touch and iPad 2. A Mac client for FaceTime was also released, curiously delivering very similar functionality to iChat but in a different, standalone app.
FaceTime uses the same open technologies as iChat does for video chats, but rather than being tethered to AOL or another IM service for "buddy" discovery, the system uses phone numbers or email addresses to establish video connections. This makes FaceTime more like a phone call (or Skype) rather than an IM chat service.
FaceTime does not monitor and advertise users' status, making it more efficient than conventional IM on a mobile device, as there is no background user discovery process. Instead, when a user attempts to make a FaceTime call, the system triggers a push message (using the same XMPP PubSub technology Apple uses to power iOS push notifications) to the client, which can then ring, alerting the other user that an incoming call request is being made.