As you probably know by now, Apple placed an order for 100 million NAND chips from Samsung recently. This order included 16Gb memory, as it turns out, though it was initially thought to only include 8Gb chips.
The 16Gb chips allow for 2GB of storage space, so this could point to the imminent release of 32GB iPhones, which would make an appearance sometime this summer. Sure, it's possible that more 16GB iPhones could be on the way, but that seems unlikely, especially since the company has been working furiously to unload their current inventory.
We'll just have to wait and see where the 16Gb memory is used, but all of the iPhone 3.0 rumors floating around seem to sync up nicely with this expanded memory order. We'll keep you posted.