A couple limitations with 6u5 b07:
1. Install 6u5 Consumer, run 6u6 online installer to patch to 6u6, install
6u5 Static. If 6u6 is uninstalled, reinstalled, or converted to Static,
the HKLM\SOFTWARE\JavaSoft\Java Runtime Environment\1.6.0_05 registry
keys are deleted.
6u5 Static files and Add or Remove Programs entry are still present, it
is just not in HKLM\SOFTWARE\JavaSoft\Java Runtime Environment\

2. An issue with upgrading in place with the off-line installer.
Consumer upgrades with the off-line installer are not removing the
previous consumer installation. Two entries in Add or Remove Programs
and the registry point to the same directory. Only one can be removed
with Add or Remove Programs. The other must be cleaned up.
Another symptom of limitation 2 above:
JQS is running, the FilesInUse dialog is not displayed, and JQS is running when trying to unzip core.zip.
During install of 6u6 over 6u5:
Product: Java(TM) 6 Family -- Error 1722.There is a problem with this Windows Installer package. A program run as part of the setup did not finish as expected. Contact your support personnel or package vendor. Action unzipcore, location: C:\Program Files\Java\jre6\zipper.exe, command: "C:\Program Files\Java\jre6\core.zip" "C:\Program Files\Java\jre6\" ""

Rakesh encountered this on 10/31 and it was discussed in an email thread.