Just downloaded all the latest updates, and I am happy to report that, at least for me, the only plugin that didn't work with 64-bit Cubase 6 on Windows 7 64-bit Ultimate was Jupiter 8V. The 64-bit Mg (modular, mini) worked wonderfully, and the 32 bit versions of the others (Arp, CS8, Prophet) worked with 64-bit Cubase and did not crash. I was worried after reading all the forum posts, but 5 out of 6 is good enough for now.
Shreddage for guitars, Trillian for Bass and Superior 2.0 for Drums can exceed 4 gigs of RAM just by temselves, so going back to 32-bit Cubase is no longer an option.
Looking forward ot the rest of the plugins (especially Jupiter since it's the weakest link right now) getting the full 64-bit treatment.