I have to say, one aspect of Twitter that has surprised me with its power is its ability to get attention from service providers. I am always surprised and appreciative when someone replies to my tweet where I'm complaining about something.
When I am unhappy about something I do tend to gripe about it on Twitter. This blog itself may arrive as a tweet because the folks at dlvr.it responded when I complained about Twitterfeed not working.
The folks over at Perforce have also been paying attention, although when I come back with a followup reply I tend to get re-routed to support, who re-routes me to my local contact, so oh well.
I also notice when people aren't listening. For example, when I complained about Sharepoint user interface being, well, painful to say the least, I have to say I'm not expecting to hear from anyone with a followup.
I've even met some good folks this way. I was whining about Sonic.net (I can't even remember what about), and ended up being followed by (and following) @dane, a dedicated employee at Sonic.net, and now I'm learning all sorts of cool stuff about what sonic.net is up to. By the way, highly recommend those guys - excellent quality, great customer service, and they have some innovative services on the way (if I can trust Dane :)).