MSMobiles reports that Microsoft is introducing a new XBOX Live client for Windows Mobile based Pocket PCs and Smartphones. Details about the features of XBOX Live for Windows Mobile from the website:

Xbox Live is an online multiplayer gaming and content delivery system supporting voice chat through a headset, bundled with the Xbox 360 premium package and the Xbox Live starter kit or available separately. There is a friends list of other users, as well as a mail-like system of either text or voice messages which can be used to send a message to an offline user.

On the Xbox 360, whenever the user’s console is powered on and is signed in to Xbox Live, the user’s friends list and ability to send messages is available. On the Xbox, this is only available in Xbox Live or Live Aware games.

The system also reports friends’ activity on their system, typically the game being played, although the system supports more detailed information (the player’s progress through the game, for example)

Screenshot of an HTC device running XBOX live for Windows Mobile (via MobilityToday)