One IM'er that I follow - whom I respect & admire - is just waaaaaay over-doing it selling on Twitter. Lots of tweets, most of them essentially just sales pitches of one type or another. I can imagine this becoming "SOP" for IM'ers.
Already there are the "how to take advantage of Twitter for marketing" guides, etc. And Twitter doesn't have the community or goodwill that keeps Craigslist from drowning.
The problem, I fear, is that this will become more and more common, until the 'noise' simply makes Twitter less & less useful or attractive.
Sure, I can pick and choose who I follow, but that's not the point. The point is that it's looking more and more like so many other things that IM'ers will abuse to the point of uselessness, if not killing it entirely, at least for the IM community.
Ok, back down off my soapbox... :<0