For legacy reasons we standardized our environment on Ubuntu Server. Generally when a new Ubuntu LTS release comes out, we, like many others, start deploying any new installations on the new release while we start planning upgrades for our most out-of-date servers. When 10.04 (lucid) was released, we already had everything up to 8.04 (hardy), so it it wouldn't be terribly painful to bring everything up to the newer release. At least that was our thinking, but when we installed our first 10.04 server, we got a surprise.