WLM dev team released the Windows Live Messenger Library 2.0 (WLML 2.0). WLML 2.0 is backward compatible with WLML 1.0. In addition, the V1.0 API continues to be available with no changes. The library is available at the following URL:
http://www.wlmessenger.net/api/2.0/messenger.js and an updated documentation, with increased coverage and samples in many topics, including new samples for custom presence and custom messages.
Dev.live.com offers overviews of developer features of Windows Live and related products, as well as SDKs (Software Development Kits), and forums where you can post questions and/or find answers. We’ve posted on it before, but a shining example of a great SDK is the Virtual Earth Interactive SDK.