The first DLC is the already announced 30 VR missions, which will evidently also add a wooden sword infused with the soul of Solid Snake that will emanate sounds of the aging hero's voice. There will also be a VR mission where you control a tri-armed dwarf gekko droid as well as a side-scrolling level where you'll have to fight unarmed.
Next up, is an add-on where you'll play as Raiden's nemesis and Vamp-lookalike Jetstream Sam. It's unclear if his missions will be story-based DLC or some kind of challenge maps. Based on the two pics provided - below - they don't appear to be set in a bright yellow VR simulation and it looks like you'll be taking on a Metal Gear Ray at some point. We've asked Konami for more clarification about this expansion and are awaiting reply.
Finally, and most excitingly, the third chunk of DLC will allow you to play as robot dog LQ-84i. Again, we're not sure if this is story-based or not and we've sent in a query to Konami.
The first DLC will be available in Japan in April where it will cost ¥300 (about £2). It will be a PS3-exclusive in North America and available on Xbox 360 as well in both Europe and Japan. There's no word on whether the other DLC will make it to the west, but we're looking into it and I can't imagine that it wouldn't. Especially as Revengeance was the second best-selling game in the UK this week.