[paulgb]

> If you are already partial to a particular shortener when you tweet, you can continue to use it for link shortening and analytics as you normally would, and we'll wrap the shortened links you submit.

I really hope this habit doesn't catch on. If it does each link will have three points of failure instead of one (as it should) or two (as it will with t.co).

[fizx]

Twitter will likely crawl the final targets of the urls, so that when bit.ly goes out of business, the t.co urls pointing to bit.ly can get redirected to the canonical link. So I don't think it's quite as bad as you're thinking.

[DougBTX]

Apparently if you have a unique word in the expanded version of your url, then search for your tweet containing only the shortened url using the unique word, you will still find the tweet. I've not tested it myself, but I took it as evidence that they are indeed caching fully resolved urls.

[paulgb]

This is true. For example, few of these tweets contain the search term: http://search.twitter.com/search?q=news.ycombinator

Hopefully they'll be resolving all the way down the redirect chain.

[marcus]

Its url shorteners all the way down...