For those using 4th & Mayor, the popular Foursquare app by Jeff Wilcox, you may have noticed a bug popping up earlier this evening. Specifically when you try to check in, you get a 'What's New' pop up and you can't navigate away from it (let alone check in).

Long story short, from Jeff himself: 

"Unfortunately a foursquare web service change has impacted 4th & Mayor, says "what's new" with a blank page. ETA: Friday for a fix"

"Ah, I was a little sloppy in my coding & the 'notification tray' feature for Android, iPhone is affecting 4th & Mayor."

So that's the bad news. The good news is a fix is being pushed through the Marketplace as soon as possible and perhaps more importantly, knowing that you are not alone in the matter. Even better news? If you have a developer unlocked phone, you can deploy the update version right now from Jeff's Dropbox: download the XAP here.

Source: Twitter (1, 2, 3)