The last time I used a Mac was when my wife had one, but now that we are proud owners of a couple of iPhone 3GSes, I would like to purchase a Mac and get my feet wet writing apps for it. For my Windows and Linux development, I'm used to having maxed out workstations with a multi-monitor setup.
Obviously, I can't commit a couple of thousands of dollars to do same on the Mac. Therefore, what is a "good enough" Mac to get that will allow me to develop on without it frustrating me somewhere down the road? Any recommendations from those who are already developing iPhone apps?