Sorry to keep on making this point but I feel it's important : Delphi XE2 uses FPC. all the 'features' that mean a damn to a pascal game developer are thanks to FPC, not XE2. IOS support? FPC. 64bit support? FPC. Mac support? FPC.
Firemonkey is impressive and will no doubt be useful, but if you're not using it for menus etc then all you're doing is using FPC with delphi as your IDE.
Buy XE2 for firemonkey, buy it for superior database client development, buy it for superior Windows 32bit performance, buy it for superiour debugging.
but cross platform game development? just use FPC. they'll be using GDB on other platforms. either that or they've been very naughty and not submitted FPC changes back to the community.
EDIT : Others have stated FPC is only used for IOS support or more specifically ARM support. It is reasonable speculation to say that if this is the case, you can expect the IOS intergration to be of a superior production quality (no messing about) when compared to what's currently available in the FPC community. Also, if it is their native toolchain for x86-32, x86-64, having a complete 32bit+64bit runtimes for windows + OSX? that makes the XE2 compiler a serious concideration for me. Linux support would of sealed the deal but alas, Kylix scared them off...