Use this link to activate & get all the details: http://www.flickr.com/groups/flickrtwitterbeta/
I personally love this for a couple of reasons:
- I can cross-post via email, which is handy for updating via cell phone. The subject line of the email is the tweet and the picture is posted to Flickr and assigned a shorter URL
- The short URL comes from Flic.kr, so it's very clear where your link is pointing to (whereas with TinyURL or others, you can't tell 'til you've clicked)
- I can tweet directly from Flickr, using the "Blog This" button - it shows your Twitter account as another blog that is enabled.
- It shows the character count remaining for tweets via "Blog This"
- Easily tweet other interesting photos using "Blog This" (this assumes that you have permission - this is a customizable setting that usually only your contacts or friends have enabled, but some people allow anyone to blog their photos)
- Once people use the short URL to view my picture, they can instantly comment
- PLUS Flickr tracks all the pertinent data about where your photo traffic is coming from -- so I can see how many views were from my tweet vs. search vs. friends just browsing. Very cool.