Every Mac still ships with Xcode on the OS install disc, as do the OS X upgrade discs. Let's wait until Lion comes out before assuming that won't be the case anymore.
This was a stock machine: walked into Apple Store to buy it. (No special factory config)
Compiling SBCL and a few items from MacPorts worked fine, so everything seems consistent with what I've seen on other Macs since 2005.