Microsoft continues to invest in Virtual Earth, especially in the area of 3D, announcing yesterday it has acquired Caligari, makers of trueSpace, a 3D modeling program.  Last December, Microsoft also acquired MultiMap, a London based mapping service, and in October announced a partnership with Dessault Systems to provide 3DVia for Virtual Earth 3D. Steve Lombardi has more on the Caligari announcement on the Virtual Earth / Live Maps blog, and Caligari CEO Roman Ormandy makes the announcement on the trueSpace Community Forums.