At UDS in December, Mark Shuttleworth announced the work the Ubuntu desktop experience team is doing on notifications. Back then, I was not entirely impressed by it, but couldn't put my finger on why. I kept thinking that I would want a quick way of getting rid of a notification, which the proposed system would not have.
It just struck me that the big thing that bugs me about notifications is that they appear at all.
If I'm working on something, and there's an asynchronous notification about something, such as the network going down, or getting back up again, or there being new mail, or whatever, that's going to break my concentration. It's well known that that's a bad thing. It can take fifteen minutes to get back into hack mode.
Notifications aren't all bad, of course, but it seems to me that it is rarely a good idea to disturb me with them immediately. Only for very urgent things, such as the laptop battery running out, is it worthwhile.
A better design would be to cache notifications somewhere I could look at them when I have time. It might be a notification area icon that appears when there are notifications, which I could click when I have time.