The “cancel” link appears on any user’s profile to whom you’ve sent an outstanding friend request. Tapping it deletes the request immediately.
This is a nice addition not only for foursquare users who’ve accidentally requested the wrong person, but also for lots of early users who got caught up in the Facebook/Twitter “gather as many friends as you can” mentality and sent requests to large numbers of users they didn’t know personally, many of which are still outstanding. When foursquare tried to limit this practice by implementing limits on the number of outstanding friend requests, there was no way to delete the outstanding ones and add more friends.
Wondering who you’ve sent requests to? There’s a list hidden on foursquare’s mobile site, but don’t get too excited, because those delete links don’t work — even though they look like they do.
What do you think of the addition?