Twitterhawk : Marketing Twitter
I have read an interesting article “Twitterhawk: No Guts, No Story “ written by Guy Kawasaki. I will summarize it in two points :
1-Targeted audience: Do a Search at Search.Twitter.com for your favorite keyword .
2- Customized Retweets: Twitterhawk will response to every different tweet differently, costing you $0.05 per message.
I think its a good marketing tool, smart and effective.

Thanks for writing, I truly enjoyed reading your most recent post. I think you should post more often, you clearly have talent for blogging!
Thanks for your kind words