I have an iPhone 4 with micro sim, and am wondering if it is possible to put my micro sim into the unlocked nexus s, to function as my phone (for development purposes). If not, is there an alternative android phone that would work better for this?
The Nexus S uses a traditional SIM card slot, but you should be able to do this provided that you get a proper micro-SIM to SIM adapter. Here's what I got from a quick Google search, and as you can see they are relatively inexpensive.
Also be aware that the Nexus S will not have 3G capability on the AT&T network, as I explained in this question. This may or may not matter to you, of course.