I'm rather tired of people on my team stealing my care packages. I just want everyone to be aware that care packages are killstreak rewards, not random drops. As such you should only take a care package under one of the following three conditions:
1) It is an enemy care package.
2) The owner of the care package announces that anybody can grab it (usually due to the fact that he/she died and doesn't want the enemy to obtain it).
3) It has been sitting in the same location for multiple minutes and the owner has not mentioned that he/she is returning to obtain it.
So, in summation, get yer dirty hands offa my package!
-Hyst