Yammer won the TechCrunch 50 (so please support it!)

Please add support for Yammer. They have an open API (http://www.yammer.com/company/api) and have detailed documentation available (http://www.yammer.com/api_doc.html). Search within the documentation for "create a new message" to get to the specific section on posting an update and the attachment info.

Unlike some other requested services, Yammer took the top price at the TechCrunch 50 last fall and has a growing user base: http://www.techcrunch.com/2008/09/10/yammer-takes-techcrunch50s-top-prize/