Rafat nicely points out what's got a lot of people buzzing: that Konfabulator and Sidebar are really the beginnings of entry into the productivity software market - ultimately, the beginnings of attacks on Office.
I don't know that this is going to be such an interesting space to track, just because MS's anti-innovation/strategy decay has exposed so many obvious weak spots relative to lightweight service-based solutions, the evolution of market dynamics seem pretty straightforward (but YMMV).