We decided to install Crossover on our machine running Kubuntu, and the installation went smoothly, both of Crossover and Steam. Steam starts up and seems to work as well as it does for us in OS X. However, I noticed a problem (which may not be unique to Linux, I can't test it in OS X right now) that messages from friends do not work properly.
It is possible to open a chat window (right-click a friend in your list, choose "Send message..."), and it is possible to send messages, but sent messages do not appear, and no incoming messages appear at all. Sent messages do go through - we tested that with another account that was running Steam under Windows. But any messages sent from the Windows machine did not reach the Kubuntu machine.
Has anyone else encountered this problem, and has a solution been found?
A small edit - I should mention that I do not have this problem in Crossover 6.2 under OS X 10.4.11.