Another way to think about it: Color is "Bump" without the need to bump phones! Using various sensors, it can tell who you are next to, and then you can exchange contact info, photos, and set up an ad hoc connection. Another use could be to figure out what store you are in and offer you relevant coupons...
Suppose I have 4 Macs but only 1 developer account ($99 per year). Can I download Xcode 4 for free on all 3 machines, or is there a limit on the number of Macs per developer account? Has anyone tried this?