Originally Posted by Fallacy11
That game was only 22 minutes, and it was a defeat, I think it will be ok
This. IP is determined by two factors alone: game length, and victory/defeat.
The longer the game, the more the IP.
If you win, you also get much more IP.
Riot has already stated that the amount of IP received from these games should be equivalent to a similarly short game of Summoner's Rift. If you play 2 games of dominion in 40 minutes, you'll get the same IP as one Summoner's Rift game.
EDIT: It's amazing how silly people can be. It's obvious that the OP is trolling, trying to get people QQing. I'm seeing posts like "This should be seen by all." and "Looks like I won't play Dominion much." Are you people really that dumb? Some people already laid it out for you on page 1, and now I did it again.