The original iPad had 256mb of RAM. The iPad2 has 512MB, the same as the iPhone 4 and 4S.
As said, it only needs more RAM once they add a significant amount to the OS. Otherwise, what's the point. At the end of the day, it's a phone not a desktop computer. As long as it multi-tasks well with minimal lag (which it will due to the dual core), what would be the point in having a further 512MB of RAM sat there doing f**k all? Plus it's got a 1gig processor...more than enough.
Awesome sales figures...pretty shocked they outsold the pre-orders of the iPhone 4, by some margin too! Ordered white this time. Bored of black (no racial connotation)