I joined Twitter yesterday, and installed the Twitter Tools plugin.
Unfortunately, the “Post from sidebar” feature was broken for me. I think this was because my WordPress installation is in a different directory from the actual blog, and Twitter Tools was looking in the wrong place for class-snoopy.php.
To fix it, I had to edit one line in the “do_tweet($tweet = ”)” function of the twitter-tools.php file.
I changed the 7th line of this function to:
If you experience this problem, replace “/home/a_folder/public_html/wordpress/wp-includes/” with the path to your WordPress installation’s class-snoopy.php file.