Devmaster.net have this article doing a technical comparison of the Doom 3 and Source engines. It is more of an overview than a detailed analysis but might be worth a look if you're interested in this sort of thing. One thing it fails to address is that of network security/cheat prevention, which (in my humble opinion) is at a pretty important component of any game these days and one that needs to be firmly addressed at the engine level.

Neither of the two games have PunkBuster support (not so much of a problem for Doom 3 as it is primarily a single player game, but one that may become an issue if any popular multiplayer mods are developed), and Valve Anti-Cheat (VAC) is still not in place in Counter-Strike: Source (and hasn't been updated for many months in the original Half-Life titles).

I would like to see a comparison between the two api's personally.

Good article. I'm looking forward to seeing games using the different engines. Doom3 looked really good for the first few levels, but there are only so many sexy ways to render shiny metal before it gets old.

Can't wait for VAC2. Valve needs to place more emphasis on security.

Are the doom3 and source engines that far ahead of the farcry one?

I was amazed at the physics in farcry when I first saw it, the source and doom3 engines didn't seem to be leaps and bounds ahead.

Farcry AI was pretty good too.

Any comments?

Yeah, wait for Stalker ;)

But seriously, I think the only way to compare physics would be to design the same scenarios and implement them in each engine to test. The physics in Far Cry seemed ok, as did D3 and HL2. But whether they're comparable is hard to say without being able to test similar things.