Not a glitch, but very useful if you play with the Spec Ops kits.
C4 is your best friend. For instance, in many cases after taking a highly contested flag and you wish to continue on your way to capture another flag, it is best to throw 1 or more c4 charges on or near the flagpole. The reason for this is when you see that the enemy has neutralized the flag that you just put c4 on you can switch to the detenator quickly and blow it usually killing the people that were trying to take it.
Also c4 can be throw onto the ceiling of the first floor on some buildings and when detonated it will kill the occupants of the second floor. For example, say you have previously tried to take over flag 4 on Backstab, but you know there is 2 guys sitting near the health on the second floor watching the stairs. No worries. Get underneath them and chunk a few c4 charges onto the ceiling of the first floor, back out of the building, blow the c4, and continue to capture the flag. This can also be used directly under the flag on flag 4. But in order to have the c4 stick to the ceiling you must jump while looking straight up and then throw the c4. If done correctly the c4 will stick to the ceiling and you can kill anyone who is taking the flag at the moment. Works well for when you know there are a few guys up there. Much safer than charging in with just the SMG. (Note i know this same technique can be used on flag 3 of BridgeTooFar. Go underneath the bridge jump and throw and it should work.)
I am very new to the 360 version of BF2, but I know of quite a few tricks on the original version that I would be willing to tell. Includes how to get on top of flag 4 on backstab without a helicopter by jumping from other buildings, the bridge glitch on BridgeTooFar (not sure if they have taken this one out or not), and a few others. Just send a request to XxCorrupt07xX.