Hi,
I have already noted that I work on extension which allows displaying of user online status, see https://bugzilla.wikimedia.org/show_bug.cgi?id=32128, Krinkle come with idea that it could use ajax on user pages for status bar in order to avoid cache issues while keep performance of interface (if cache would need to be suppressed it would have probably negative effect on performance althought it would happen rarely). I like that idea, however I have no experience with ajax. If anyone who understand ajax wanted to help it would be most appreciated!
Thanks