Windows Live just released its first official product, taking the beta tag off Messenger and opening it up to the other 90% of its users.
Windows Live Messenger adds a new UI for 240 million users of the application formerly known as MSN Messenger. The new IM client allows you to place a call from your PC to any phone, connecting PSTN networks to the soft client through a relationship with Verizon. All Messenger contacts are synchronized using the Windows Live Contacts across Mail, Spaces, and soon other services such as Mobile. Offline messaging is in there too.
My favorite new feature is the FolderShare integration. Users can share a folder on their computer with anyone on their contact list. Your coworkers can access the latest files for a project or your mom can view your latest photos at any time, just as if they were a folder on her own computer.
The next big feature release should include interoperability with Yahoo! Messenger. The feature is currently being tested internally by both Yahoo! and Microsoft.