Just upgraded to Snow Leopard, installed Xcode 3.2, then installed iPhone SDK 3 for SL.
In a project, I now get the following error on build:
It looks like you're picking up libraries from /usr/lib, which is wholly inappropriate for the iPhone SDK. I would assume you've changed your build settings to add /usr/lib to the library search paths. This should be completely unnecessary in the first place, as /usr/lib is in the compiler's standard search paths, but if you need to have a modified search path like this, make sure to use $(SDKROOT)/usr/lib instead.