I've written a little script to pipe Twitter in and out of Jabber. I'm using Adium on OS X to get these messages: and I have it so when Adium is in the background, it pops up a Jabber notification. I like this behaviour, but I don't want it to happen on the account I'm using to send the tweets into Jabber - because, you know, having a Growl notification pop up every time someone tweets is quite annoying.
In Adium, I've found out how you can set specific notifications for a contact, but it only seems to have the ability to add extra notifications for a particular user, rather than the ability to remove notifications. I could make my defaults set to be the least noisy I ever want, but then I'd have to replicate the settings I want for normal people for each person (possibly by hand) when all I really want is for my Twitter bot to be quiet while letting human contacts use the default set of notification preferences?