You won't see the partition through Finder or Terminal directly.
You can see it either by running this in terminal:
diskutil list
Look for something that looks like this:
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *120.0 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_HFS MacHD 119.2 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
You can also see it via the System Information screen by clicking on the Serial ATA section and selecting your boot device.
By the way.....I have no idea whether a clean install creates it or not.....I would guess it would, but I did the upgrade.
-Kevin