Seeing it's free this week, I went to select it from the store. There was no selection to add it to the cart. I tried on both my PS3 and through the PC store but was unable to do so on either. Did it get pulled?
The game is currently free in the PS Vita Playstation Store only. It is currently unavailable in the PS3 and SEN Playstation Stores. I have no idea why. Perhaps it is some Vita-specific promotion. Where did you hear that it was free this week? There was no mention of that in the Playstation Store update, at least not on this web site.