Kevin - I'll attempt to explain.
Sin0822 is stating that P67 and Z68 motherboards are very similar. So similar, in fact, that Gigabyte have actually re-labelled some of their performance P67 boards as Z68 ones.
He states that the only genuine Z68 motherboards are those with onboard graphics outputs. These models have the H suffix, eg. GA-Z68X-UD3H-B3 as opposed to GA-Z68X-UD3-B3 or Z68X-UD3P-B3.
Personally, I don't believe him since Z68 has other distinguishing features, and someone would notice resulting in a nasty law suit for Gigabyte.
However - even if this is the case, then most users won't actually notice because it's unlikely that they would be trying to use LucidLogic's Virtu software.
Virtu allows the user to use both the on-board and discreet graphics that their Z68 system has, depending on the circumstances.
It has two options:
If you plug your monitor into the on-board graphics outputs of an appropriate (For gigabyte, that means 'H' suffix) motherboard, Virtu virtualises the discreet card(s), meaning that they are only used in 3d games and other demanding applications. The rest of the time, the cards run at idle - saving power and run-time, and keeping the system cool while the Intel 3000 graphics do their thing.
This option requires the games you run to be on the Virtu whitelist which is very limited at the moment, so it's not really a good choice for most power users.
The second option allows you to use all the functions of your discreet cards - eg. AMD's Eyefinity. It involves plugging into your discreet card's outputs, and Virtu virtualises the onboard graphics, which are basically only used for video encoding.
This method is preferable to those who want the full use of their discreet cards, but it doesn't allow the power saving features that Virtu advertises heavily.
If you don't do video encoding, then I doubt you'll need Virtu at all.
Hope that goes some way to helping, before Sin gets back here...