You don't run pvcreate on lvm partitions. You run pvcreate on the block devices that will be added to the volume groups.
You sure can run pvcreate on a partition, for example /dev/cciss/c0d0p1 instead of /dev/cciss/c0d0 and the use of it for example, creating a partition of "Type" LVM so that it's obvious what's going on:)
man pvcreate
/snip Each PhysicalVolume can be a disk partition, whole disk, meta device, or loopback file. /snip
jlc