We can assume that multiplayer was headed to PS Vita games, Uncharted: Golden Abyss and Resistance: Burning Skies? However, there is some confirmation...sort of.
asked one of the developers about the inclusion of a multiplayer option on Golden Abyss. They reported that he said that "we should expect 'something different', and that an official announcement will be coming soon." Hmmmmm...something different? That is quite interesting.