I mean games with serious graphics and gameplay like the PS3. I would have thought the iPad had the resources terms of processing power together with HD screen for game designers to take it as a serious gameing device. Take Need for Speed - the graphics is horrible compared to the PS3 version of the same title. The game mechanics also feels a lot different as in when you drive; it just does not have the same feel as when you play it on the PS3. So far I have found the iPad to be good for quirky games like Angry Birds, but not serious gaming.
The dev's would have to do that for most part. Wait for the summer time you will see tons of games out on iTunes.
It's not gonna happen, most ps3 games are between 10 to 50 gb in size, plus they would take forever to download in app store.