Wi-Fi hotspot detecting applications are the latest on Apple's list of verboten apps, and even developers are being left in the dark as to why.

Wi-Fi detection is something of a niche: there were never more than a handful of such applications in iTunes. But now even those have vanished as Apple decided they were using a "private framework", and has pulled them off the shelves without explanation or apology.

Only applications that actively scan have been pulled: those that use a database of hotspots combined with GPS data garnered from the handset are still available. Users can manually search for nearby hotspots in the usual way, but applications that do the same thing are no longer allowed.

"We received a very unfortunate email today from Apple stating that WiFi Where has been removed from sale on the App Store for using private frameworks to access wireless information," explains one developer, though Apple has apparently declined to explain exactly what rule the scanning applications are breaking.

It's possible that this is just part of Apple's ongoing tidying of the iTunes store, enforcing rules more stringently, but we can't help wondering if the "private framework" is one that won't be available on the iPad and Apple is trying to get as much compatibility as it can before the iPad is launched.

For the developers it doesn't much matter either way: their work is wasted as the applications can't, legitimately, be sold without Apple approval. So they'll have to be shelved against the hope that Cupertino changes its mind at some point. ®