The best I can figure out this is related to Apple's press release last week identify the ability to now download older versions of updated apps on older iDevices.
For example, on my iPhone 3G I am able to now download SoundHound and MyStarbucks even though those two apps have gone through a couple of updates since 4.2.1
What I am guessing we are seeing now are updates showing available to you but in actuality they're not. For example, an update on Wikipanion+ is only for 7.0 yet on my 6.02 iPhone 5 it shows the available update yet when I attempt to do so the badge clears and the update is no longer 'available'.
This may seem convoluted, yet I see the reasoning behind Apple doing this- at least for now.
They're likely to change this procedure when enough customers complain