Post-release testing showed up a variety of bugs in the images produced for the 6.0.1 update release:
1. Wrong installer code used for the small CDs
The script used to build the netinst and businesscard CDs was misconfigured, and was using the testing (Wheezy) version of Debian Installer instead of the correct Squeeze version.
2. Incorrectly sized DVD images for some architectures
3. Update CDs and DVDs missing Packages and Sources files
More here