Yes it is. The 16gb and 32gb are out there. Just not many stores are carrying them because of the price. Here's one that does have them:

http://www.mobymemory.com/products/S...emory-Card.asp

EDIT: Oooo. Hold onto your britches, I just got word about some big announcements are due out soon in regards to high capacity cards. I can't say my source, but they include a 64gb and 128gb microsd, and 32-128gb minisd.