Not surprised at all that the 360 version of Portal outsold the PS3 version. Called it as soon as the extra steam copy was announced exclusively for the PS3. At this point, no amount of exclusive content will make the PS3 version of a multiplat game outsell the 360 version, short of the 360 version being completely unplayable. Even if that were to happen I think the 360 version would still outsell, you would just get a lot of returns.
More the software, I think. Certainly, April offered no compelling reasons for anyone who didn't buy the system at launch to buy one. May will be pretty much the same (I don't expect DOA to have much of an impact on hardware sales), but June will be much more interesting.
Re: Portal 2
People need to keep in mind that Xbox 360 owners got The Orange Box first (and a well done port too) and the exclusive Still Alive which still manages to chart in the weekly sales.
PS3 owners only got The Orange Box, late and along with harsh words about the quality of the port. So the added bonus if anything made some 360/PC owners change to the PS3 version, more than attracting new users.
So, in many people's mind Portal is an Xbox 360/PC game.
I'd say both. The lineup took the wind out of people's sails and made them look real hard at the system for 249.99. And once that launch period euphoria passes and the buzz wears off, it takes a compelling reason to purchase. 3DS isn't offering many reasons at the moment. Makes it easy to have resolve at the 249.99 price.
I think ultimately, we overestimated the impact of the free PC copy and didn't consider some of the things the PS3 version had going against it (not many PS3 only users likely played Portal on the Orange Box....Valve games usually releasing on 360, PSN, etc)
If it doesn't indicate # of sales ordering, I would guess it indicates $ sales order. Since 360 and PS3 games cost the same, I think it is safe to assume that the order indicates # of sales order when comparing these two systems.