We updated dCache this morning to 1.9.0. Now that sounds like a major jump but reading the release notes it is only a minor step up from the 18.0.15pX series of releases.
The upgrade itself was trivial, just installing the new dcache-server rpm and running install.sh across all the nodes.
We also took the opportunity to update the version of Postgresql on the head node from 8.3.1 to 8.3.5 using rpms from pgsqlrpms.org. I'm hoping that I will now be able to use their prebuilt slony-1 rpm to set up master slave mirroring of the databases from the dCache head node to a live mirror node.
Finally we updated the SL version of all the dCache nodes to SL4.6 from a mix of SL4.4, SL4.5 and SL4.6. We're now using the SL-Contrib xfs kernel modules on all nodes and the Araca drivers complied into the 2.6.9-78 series of kernels on all nodes with Areca raid cards rather than our own builds and have had no issues.