Another factor could be that the presence of the entertainment industry means there's another huge, highly entrepreneurial game in town. I remember Kathy Sierr

Another factor could be that the presence of the entertainment industry means there's another huge, highly entrepreneurial game in town. I remember Kathy Sierra's post about the "hollywood model", where you always get fired at the end of a project because that's what happens when a project ends. Your job security is 100% a function of your reputation and body of work. While successful and creative software companies don't (necessarily) "end" the same way a film or album might, I have noticed a similar pattern among a lot of the creative workers in the bay area startup scene. I wouldn't call it "job hopping", since these folks typically stick around long enough to see the project through, but they won't stick around to maintain a project either. They will leave to find something in a more creative growth phase. The film industry does provide for this kind of career (including in high tech)... and actually, it's pretty difficult to get "credit" for your work as a programmer (I suspect that this frustration alone contributed substantially to the rise of open source projects), whereas if you work on the tech side of a film in a meaningful role, your name will appear in the credits.