I have absolutely no idea exactly what problems these fix, but Nokia 808 owners might like to look in SW Update on their phones - available now are a couple of minor updates, titled
Lotus Notes Traveler? And that's the best known application that's had its compatibility fixed? Obviously some low level PIM field issue fix, note that the fix is only 4k (below).
The Big Screen update is a lot bigger, so presumably a replacement application with bugs fixed.
As ever, find 'SW Update' on your Nokia 808 and it'll scan for updates and show these automatically.