This isn't just Dropbox deciding to hire Guido, it's Guido deciding to work for Dropbox and, perhaps most interestingly, deciding NOT to work for Google anymore. Surely a company the size (and type) of Google could come up with some pretty amazing projects for an engineer like Guido to work on if he got bored but, for some reason, Guido left. The reason could be something as boring as a big raise or a shorter commute, or something more interesting (a new internal policy to start replacing Python with Go, a clash with one of the big shots that leaves Guido forever on the shelf in the celebrity trophy case, or whatever.)

I'll have to admit I'm curious.