Popular social check-in service Foursquare is going through some changes, and the most important of those is that the old v1 API is going dead, as we've known since March. Older apps, especially abandoned ones, will stop working then, as will any newer app that hasn't yet upgraded to the new API.
From AboutFoursquare's post:
Anyone with an app that’s still using version 1 will now see a message from “Jimmy Foursquare” in their friends list that reads:
Your foursquare client is out of date! If you don’t upgrade before August 1st it will stop working.
If the app isn’t updated to the new API by August 1, users will no longer have access to any of its foursquare capabilities. Foursquare has said there will be “no exceptions“ to this rule.
A few notable apps are currently showing the message, including Seesmic and Tweetdeck. Both are Twitter clients that show foursquare location information alongside your Twitter Feed.
App developers who’ve already made the transition to version 2 report that the move is relatively easy to complete.
It's a really good gesture that the users of apps that will go dead have a warning in their apps, so they have a chance to switch to an updated app if theirs doesn't seem to be getting an update by the deadline. I'd love to see this sort of behavior whenever an API is being deprecated for a new version. Twitter could have done this for last year's OAuth switch-over, for example. I look forward to more APIs finding sensible ways to handle these sorts of changes.
Foursquare v2 was made public in December, with v1 officially deprecated at the same time. In March, Foursquare gave V1 an expiration date of August 1, giving developers over four months to make changes.