I saw this on a few sites but this one was the most thorough.
Huge news from the Real-Time Communications product team at Microsoft. First, we'll be getting a Live Communications Server client for Windows Mobile devices sometime in the second half of this year. I've been happy using the MSN Messenger client that comes with the Windows Mobile-powered Audiovox XV6600, but being able to communicate with other corporate LCS users will be a huge win-- right now, if I want to IM with someone inside Microsoft's perimeter, I have to dig out the ol' laptop. MS hasn't yet announced pricing or functionality; I think it's safe to assume that the Windows Mobile client will have a subset of Office Communicator's functionality, in the same way that Pocket Outlook is a subset of desktop Outlook.
The other news astonished me: Research In Motion, producers of the BlackBerry line, have signed an agreement with MS to produce a Live Communications Server client for the BlackBerry platform. This is terrific news for the LCS team, and great news for BlackBerry users who want to combine their existing mobile e-mail service with IM and presence. Of course, it raises the bar for the Windows Mobile team, who now have to contend with the loss of what would otherwise have been a significant capability advantage. With Magneto around the corner, though, I bet they have some other tricks up their sleeve.