Eurogamer caught up with Hideo Kojima at Games Convention '08 and asked out of the blue if Metal Gear Acid, the PSP-only, turn-based version of the series, would ever arrive on PlayStation Network. Kojima's answer was noncommittal, but not a brush-off either:
"I'll say yes to that idea, but not because it is already running or anything", Kojima told Eurogamer when asked about the possibility of porting the turn-based strategy titles to PSN.
"I'm just saying yes because it's possible, I think it is possible. Sorry to say we don't have specific plans at the moment, but it is possible, yes".
Wikipedia points out that the two games in the Metal Gear Acid series are non-canonical.
MG Acid for PSN "Possible" -- Kojima [Eurogamer]