If you want to get someone off their camping perch there are a few ways.
If they're on your team:
1) Don't give them ammo or health packs.
2) Cover them with C4 and set it off, the dust cloud it creates is big enough that they'll have to move.
3) Launch smoke grenades into their camping area.
4) Blow up the tower they're sitting in. Suicides are awesome.
If they're on the enemy team:
1) Mark them (in Normal mode), that's what its for, plus, everyone on your team can now see them. Press the Back button on the Xbox 360.
2) Blow up the tower they're sitting in. Destruction 2.0 kills are awesome.
3) Shoot them. Duh.
4) Use the Kill Cam (in Normal mode), if you know the map well enough, you can pin point their location based off of visual markings.
Now, don't go around just C4ing and Smoke grenading all the Recons who sit around on your team. Being a Recon while on the attacking team still has its uses. Spotting, Mortaring, and defending objectives while you attack are just a few.