Could this have to do with the change of the default shell, maybe…?
Originally Posted by http://www.ubuntu.com/getubuntu/releasenotes/804
/bin/sh is now dash
- To improve overall system performance, the /bin/sh shell in Ubuntu 6.10 and later is dash, rather than bash as it was in Ubuntu 6.06 LTS. This may cause compatibility problems for local shell scripts. Please see DashAsBinSh for more information.
This stopped me from jumping right into it in the first place — plus I do not like the idea of upgrading a running server the day after any new release. So, this will all better be testet on a VM-Install beforehand.