i believe this is different than what the OP stated.
using the SL to wipe your drive, then install, still has this disk checking your OS before installing.
The verification occurred as soon as you did your wipe process.
I'd like to clarify the process I used (just incase people were wondering).
1) I booted up with my UTD disk in
2) I erased my entire HD using Disk Utility (I had a boot camp partition I wanted to get rid of anyway)
3) I turned the machine OFF
4) I turned the machine ON
5) I installed following the standard menu
Note: I used the UTD disk on the mac that it was intended (2009 iMac: Imac9,1). I think some people are trying to use the disks on Macs that aren't what the UTD was ordered for.
So I could only imagine it uses something like one of the following verification systems:
1) Sees if your Mac matches a list of "new" macs (ones that came out within X months of SL being released)
2) Sees if your Mac matches a specific hardware version; this would require each UTD disk to be system locked though (My UTD would only install on a iMac9,1)
3) It checks for the exisitence of the GPT/EFI partition on the system (which would identify either Tiger or leopard was installed, or someone was really good with hexedit/diskutil)
4) When I erased my drive, it put some piece of information on my EFI or new partition that stated I had leopard or erased with snow leopard installer after previous verification.
It could be any combination (or a completely different one for that matter) of these checks, but either way, it does a clean install like I wanted the disk to do.