source:http://www.tips4mac.info/?p=1083
Looks promising. I've been using the Hahlo/Fluid/Growl mashup, and Scalaris is similar and far easier to set up.

One problem with Scalaris right off the bat is that the Tweet field has no character count. Instead, once you've reached your character limit, you just can't type anymore. I'd rather see an unlimited field with a character count, so you can type your tweet and then edit as needed. Doesn't seem like it would be a hard fix.

I like Growl Twitter solutions in general. They are lightweight and unobtrusive. My one complaint is that URLs are not clickable in Growl notifications. I hope Growl can implement this at some point.