Will some of these developers start porting their games to the Mac now that they are familiar with development on the Mac and already have iPhone versions of their games?
Developer familiarity doesn't seem to be a big problem with games. Most PC games are written in DirectX, which doesn't have a real alternative on the Mac side. Similarly, the real novelty of the iPhone is the UI. The Mac UI is fundamentally the same as the PC.
That being said, as long as Mac market share keeps ticking up a point or two a year, more developers will invest.
I have no idea how the smaller game studios view the Mac, however keep in mind that the iPhone and Mac are very different platforms, and games that work well on a phone may not translate well as a desktop gaming experience, especially considering what people expect of their games in this day and age.