PS3 and Xbox 360 have a similar number of games on them. As for exclusives you can fairly bet that for the most part exclusives will be first party and second party titles only. Any 3rd party will be timed exclusive only.
There are currently 772 games (multiplatform: 621; exclusive: 143; console exclusive: 8) and 15 cancelled games on this list as of January 14, 2013.
There are currently 959 games (multiplatform: 757; exclusive: 123; console exclusive: 79) on this list as of June 06, 2013.
That's with Xbox having a year longer on release and having 5 months more info collected for the list.