Rumour has it that Bethesda has mothballed, or perhaps even permanently canned the Oblivion destined for the Playstation Portable. According to rumblings, Climax's Portsmouth team, which was working on the game, has been recently plagued with major production problems and was running increasingly late.
Fortunately, it doesn't look like this will have any effect on Silent Hill Origins, which is being worked on by a separate team and appears to be shaping up nicely.
Checking in on retailer GameStop's site it looks like the game is showing a December ship date, pushed quite far back from the original Spring 07 goal, which supports the delay but not the cancellation. More on this as it develops.