R2 is officially out. It launched mid September. We had a couple guys from Microsoft in our office last week talking about the BizTalk roadmap. There definately will be another release, most likely based upon the WF instead of XLang. They said don't expect it before 2009.
Also you may find it encouraging that MS is looking to hire another Product Manager to help support the release of V.Next which they say has a scheduled release of 2009