@Xoj: No it's not. They need to meet a certain graphical level and go through the quality control process. I don't know the specifics, but atleast high-definition graphics is required and on 360 there is some XBL requirements in general.
Obviously, being a good game isn't enough, since Capcom needed to make HD version of Megaman 9 for XBLA and PSN.
I don't know why are you bringing out single games, when it obviously isn't the trend. World of Goo had a dev team of two guys, who spent 10 000 USD to create the game. Naturally, most of the games aren't done that way, so pointing it out was rather pointless.
Ei Kiinasti.
Eikä Japanisti.
Vaan pannaan jalalla koreasti.
Nintendo games sell only on Nintendo system.