If i'm im'ing or tweeting with another team member about a trello card, is there a way for me to say 'Hey look at this card: http://trello/123xyz' so that they can go directly to the card (assuming they are a member of the board, etc) -- rather than asking them to go find the card based on assignment and search for the title?
Yes. When you click on a card and it opens, you can just copy the URL.
The URLs are very long,but they do work, e.g.
(Note to potential editors: I've deliberately not used Link syntax here, in order to make it obvious what the URL looks like!)
Note that as the URL contains the board name, the URL will stop working if you move the card to a different board (which was probably not possible when this question was asked).
I wrote a simple extension for Chrome which adds a "Short URL" button to the Actions menu, allowing you to one-click copy the short URL to your clipboard.
It's open source and I'd appreciate any issues or Pull Requests people fancy doing to make it better! :)
If you don't want your browser to open a new tab (at least in my experience with Chrome), you can get rid of the protocol and hostname from the link, as follows:
Also, using the board-independent link (as suggested in other answers) has the unfortunate consequence of redirecting the browser. Hitting the back button then immediately redirects the browser again. To return the the original place from which you linked, you need to go two steps back in the history. This is not the case with the link.