http://bugs.winehq.org/show_bug.cgi?id=9771
--- Comment #109 from Brandon eff4eye@hotmail.com 2008-07-05 19:12:28 --- I had problems with this in Ubuntu 7.10 with Wine (all versions). Sometimes I could get it working, but it seemed flaky at best. I upgraded today to Ubuntu 8.04 and ensured that Wine was at the latest version (actually I uninstalled and then reinstalled it). I have had no problems with it since the upgrade. Previously, to even see my list I used to have to open the friends list, change my status to online, then close and reopen the friends list. Now when I change my status, the update appears a second or two later in the window. I can also chat, and it appears to be working for me. Unfortunately, the shift+tab functionality during a game still does not appear to work.
If we are unsure if this a networking issue or not, it may be useful to get some netstat output. If someone out there could open Steam friends (maybe even open a chat window to someone too) and immediately take a netstat dump (for example: netstat -na > before_working.txt) then chant some incantations and play with it until it starts working. Once you are sending and receiving messages take another netstat snapshot (netstat -na > after_working.txt). Someone could then compare to see if there are any glaring differences. Not sure if it is overkill, but using "netstat -nap" might be even more useful since it will show the program name.