Oh man... more bad news about the PlayStation Vita launch. It's been revealed that memory cards are an absolute must if you're going to purchase a PlayStation Vita.
One initially appealing feature of the PlayStation Vita was that games will allow save data and DLC to be stored on the game media. But that's only applicable to some titles. Others won't allow this, forcing you to purchase expensive memory cards to save the game. Worse yet, some games won't even run without a memory card inserted.
Launch titles such as Uncharted: Golden Abyss, Hot Shots Golf 6, and Ridge Racer will all require a memory card. So if you're looking to avoid the added cost of a memory card, you'll want to stick to Ultimate Marvel Vs. Capcom 3, Dynasty Warriors, or Shinobido 2.
Memory cards aren't cheap, especially for cards with a large storage capacity. A 32GB memory card will run you upwards of a $100 or more (they're currently listed for $129.90 at Play-Asia)