While it's true that some details are still being worked out, the following
is the intention:
a) You post the link http://f.ws/tco within a tweet
b) Within the published, text component of the tweet, you'll see the t.coURL
c) within the entities of the tweet, you'll see your http://f.ws/tco link
On the list we were told:
our current plan is that no user will see a t.co URL on twitter.com but we
still have some details to work through. the links will still be displayed as
they were sent in, but the target of the link will be the t.co link instead.
and, we want to provide the same