Upgrading to Mountain Lion -- migration document changes?

[Jeremy Lavergne]

> Really? No 10.6 SDK in Xcode 4.4? Not even optionally? I'm surprised. I thought there were previously SDKs for two older versions of the OS in addition to the current version.

From my clean installed of xcode 4.4 and command line tools, these are in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs:
 * MacOSX10.7.sdk
 * MacOSX10.8.sdk

Interestingly, the 10.6 Core Library is available (documentation) inside Xcode as a download--but no SDK in the non-documtation downloads.