Yesterday at the VSLive keynote address Soma announced that Visual Studio Tools for Applications (VSTA) would be released for the first time publicly. The Visual Studio SDK CTP includes the VSTA CTP. This will be available this Friday, February 3rd.
Link to eWeek article:
In a keynote address, S. "Soma" Somasegar, corporate vice president of developer tools at Microsoft, said that in the next week or so, Microsoft will "make the first CTP [Community Technology Preview] drop of Visual Studio Tools for Applications."