I love the scene in the Current TV Twitter video where he asks "Who are you shouting at?" http://current.com/items/89891774_twouble-with-twitters.htm
Twitter is great, i use it personally and we also use it for www.LiveChatConcepts.com to allow people to invite friends via twitter to come join them in the chat room that they are currently logged into (eg tonight I'll be watching the #Mets @ #Giants game at 10.15pm at www.LiveBaseballChat.com so i'll be able to invite my twitter contacts to join me then by updating my status).
However is Twitter the right medium for 'dialog'?
I'm finding that it's a great medium for one way alerts but when you try and use it for building communities and getting to know people like http://tweetmeme.com/?category=sports-baseball that it's falling over.
Personally when i'm hanging out with friends I prefer to talk rather than shout so if you are into baseball come and check out www.LiveBaseballChat.com