Sony has released details about which PS Vita games will need to be saved on memory cards and which will not. The reason that this is so important is that PS Vita games that support memory cards are the ones that will definitely be able to receive updates and DLC.
PS Vita games that do not need to be saved on memory cards will not even support that function, but will instead store save files on the game cards themselves. This is perhaps why many of these games will not support DLC. Yet, Sony has suggested that some of these games that do not support memory cards will be able to get DLC, but the details for how this will work or how large such DLC will be have not been released.
In the meantime, here’s a list of games that will require memory card saves (and thus be likely to support DLC):
@Field, Uncharted: Golden Abyss, Dream Club Zero, Disgaea 3, Hot Shots Golf 6, Monster Raider, and Ridge Racer.
These are the games that support saves to the game cards themselves:
Asphalt: Injection, Ultimate Marvel vs. Capcom 3, F1 2011, Dynasty Warriors Musou Next, Shin Kamaitachi no Yoru, Dark Quest, Shinobodo 2, Power Smash 3, BlazBlue Continuum Shift Extend, The Michael Jackson Experience, Mah-Jong Fight Club, Let’s Try Bass Fishing: Fish On Vita, and Lord of Apocalypse.