Well, VMWare already knows a bit about guest partitions. It allows you to mount a NTFS partition, and allows you to shrink the partition (while the VM is powered off).
Just supporting NTFS and FAT32 will cover 99.9% of windows VMWare usage. Then there are only a few popular linux partition types.
Rearranging partitions is seldom done. Most software just allows grow/shrink. It would be very helpful. VMware should conduct surveys of what people want actually...