Does uncleared usually mean that you cannot spend the money? Because you can technically spend 0/unc, but not in the GUI and you can spend 1/unc. Maybe it should just say 0 confirmations, 1 confirmation ... 6 confirmed, 7 confirmed....
As it is it seems like there is something magical about 6 when there is not.
Well whatever the GUI decides at the moment. Uncleared deposits would be money you've received but can't spend yet. Uncleared withdrawals is money you've already spent, but hasn't been received by the other party yet -- a decent client will prevent double spending attempts by stopping you from using that as well.
In other words, your cleared balance is what you have available to spend right now; and your uncleared balance is what you could expect to have available tomorrow (or whatever the clearing time is).
The uncleared bits can't say anything about confirmation count because some uncleared funds could have 2 confirmations some could have 3, some could have 4...