How large is the app? More than 300mb?
It was facebook and whatsapp, so 14Mb and 7.9Mb, AVG says I now have 261Mb free after downloading them which would make sense for the 260Mb needed free for app installs, I'm guessing its a bug in settings>apps? I'll try installing some more apps and see if they download.
Edit:- Let me download over 60Mb of apps, maybe AVG shows how much storage I have left on top of the 260Mb required space? As for facebook and whatsapp when I've had that error before it was those two as well, maybe its just a google play bug.
Edited by Gibson.1, 22 January 2013 - 08:53 PM.