The post install configuration fails if you configure two interfaces as such: eth0: dhcp, active at boot eth1: active at boot, static address, gateway, netmask, etc. It APPEARS as though the dhcp requests are being sent out through the statically configured card instead of the dynamic card. This is based on watching for activity on the two lans as the pic is configuring the network interfaces... there is traffic on the eth1 lan (this was the only machine powered up at the time) but there was not activity on the eth0 lan (cable modem). This was on the updated boot disks in the errata.
Have you tried the anaconda errata which addresses this issue?
This is a pump bug that pump 0.8, ftp://people.redhat.com/ewt should address. Plesae let me know if it helps.