>>By the way I just looked for some info on google and I learned that Ray Ozzie was one of the creators of Lotus Notes. Ray Ozzie is now a chief software architect for MS.
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>My other question is - how popular it is and how long would it take me to learn it?

From what I know there are big compagnies using it already. I had a user's group meeting where Groove was presented and the next day I installed it and started using it without formal training.

Very easy to install and very easy to use.