The Nexus line is, as you know, Google's line of phones. They are incredibly developer friendly. Rooting and unrooting is very easy on both on them (at least compared to rooting on other androids)
http://www.lockergnome.com/android/2010/12/16/rooting-guide-samsung-nexus-s/
http://webscopia.com/2011/04/rooting-nexus-s-to-android-2-3-3/
http://techie-buzz.com/mobile-news/complete-guide-to-rooting-nexus-s.html
http://www.lockergnome.com/android/2010/12/16/rooting-guide-samsung-nexus-s/
http://webscopia.com/2011/04/rooting-nexus-s-to-android-2-3-3/
http://techie-buzz.com/mobile-news/complete-guide-to-rooting-nexus-s.html