I have a similar problem. I refuse to single partition any machine because it's an incredibly terrible idea, so I have on my laptop (and every computer) an OS partition, and a storage parition. When I installed the 7 Beta on this machine in the spot where Vista used to be, 7 does not recognize this other partition (the D drive) no matter what I do, regardless of updates as well.
As NTFS is the native FS of Seven I don't see why it has trouble recognizing an NTFS partition created by Vista. Any suggestions?
Note: I did not update from Vista but rather reformatted the C: partition to install 7.