you cannnot have it retain the connection while the iBook is closed (Unless you download software to disable system sleeping which could destroy your iBook) but changing those settings will make the connection pick up automatically and quicker upon waking
the only time reconnecting would bother me was if I still had dial-up..it would be a pain but if you have a DSL or Cable..what's 5 seconds? And if your expecting messages from your friends ..if you really wanted the message you would have stayed there and waited for it...lol
I gues sometimes its useful if your downloading something and want to just close the lid. But, just lean the screen as close to the keyboard without triggering the mechanism and that way the screen will shut off after so many minutes and now one can see your screen
I think that's stupid, as well. When I leave for work in the morning or whatever, I close the lid out of habit, and it disconnects everything. Sucks if I wanted to be downloading something, or in my case, I like to leave the messenger connected all the time so I can come home and get messages from friends. Yeah it only takes a few seconds to reconnect but it's still a pita.