On beta1 custom install from cdrom1, I selected to use fdisk to define a single install partition (2000M). When I switched to the next panel, anaconda would not let me 'edit' that partition -- claimed file type(?) wrong. I was able to delete the partiition (on hda) and define a new partition. The install then proceeded.
I have found my "problem". Apparently, beta1 only supports ext3 partitions. I had had defined and tried to use an ext2 partition. If this is suppose to be the way it works, close this. If it should be able to support both ext2 AND ext3 partitions (which is the way I would like it to work), then leave this open.
We should now properly reread the partition table after you've run fdisk. Note that parted still probes for a filesystem type so if there was a partition previously at that location, the type may be displayed as that, but it can be changed by editing the partition.