It seems Sony will be using Resistance 3 to promote other first-party games. The game will come with three demos, according to the BBFC.
The British rating board's listing for Resistance 3 mentions that it will ship with demos for Killzone 3, MotorStorm Apocalypse and inFamous 2. There are actually two versions of the KZ3 demo: one with stereoscopic 3D and one without.
It makes sense that Sony would want to promote its high-profile games from the first half of 2011. MotorStorm Apocalypse and inFamous 2 are both still fresh releases, having been released in May and June, respectively. Demos seem like a good way to get the word out for these games before the holiday season.
That being said, it's disappointing that they're only including demos for games that were already released. Resistance 3 arrives at the start of the fall, right before a couple other big PS3 releases. Twisted Metal is due in October and Uncharted 3: Drake's Deception will be released a month later. Would be nice to get a demo for one (or, why not, both) of those games. Maybe they're not planning a demo for either, though.
For what it's worth, Sony hasn't confirmed that these demos will be included in the game. It's possible that they won't appear on the game disc after all. However, because these games already on the market, Sony probably didn't feel these demos were worth announcing. Just don't uh, get too excited.
Resistance 3 will be released on September 6th in North America and on the 9th in Europe.