Apple also bought Logic, Final Cut, Shake, some touchscreen firm and of-course NeXT (which provided the base of OS X) among many other things throughout the years (I believe even iTunes is based on another application Apple bought). Apple improved everything before (re)releasing it, and I imagine (all though I don't know) Microsoft does the same.
Although, I did prefer CoverFlow's interface previous to iTunes inclusion (although the fact it was included and not an add-on was a step forward).
Also I think Silverlight could be a good thing for OS X, as it will eventually include DRM. I'm not a fan of DRM, but it will mean we can watch paid-for content and solve the big problem of MS not releasing their DRM for OS X and Apple not licensing FairPlay. It's not a perfect solution, but things like BBCs iPlayer and streaming movies (NetFlix et al) could take advantage of that.
EDIT: As for Tafiti... not a fan. I like the idea, but the implementation needs a lot of work. Type your search terms on a scratty piece of paper... with a typewriter font? Then that moves out of the way and you get a clipboard/old drawer looking thing displaying your search results... next to a scratty piece of paper, under which is a pretty cool look looking glass turntable, and behind it all is a modern, abstract background. Are they going for the retro look, or the ultra-modern look? You can't have both on one page, it doesn't work.
Tree view? Looks cool; useless for viewing search results... and yet another graphic style in the mix.
As a concept; a sort of tech-demo of Silverlight it's pretty good, but it's nowhere near a final product yet.
