Would be happy if a link u just tweeted was not tinyurled or bit.ly? Most of the designers may know abduzeedo http://abduzeedo.com and he has a twitter profile. He just did a tweet, you can see it: http://twitter.com/abduzeedo The one which says: now notice that his link is NOT masked...anyone know WHY? and would u be happy if this happened to u? i mean your getting a backlink from TWITTER
Twitter is nofollow. The only reason people use tinyurl on twitter is because most urls are too long to use in the 140 character restriction. If the url is already a short one, no reason to tinyurl it.