In competitive gaming circles, having greater than 30ms difference between teams on a server was ruled an "unfair server", so it is interesting to read the truth about pings in the online MW2 experience.
The truth was supposed to be that the IW.net experience was going to be far superior than the one getting on dedicated servers. Far from it in my opinion. Now we have some numbers to back up that opinion.
SarahB on IW's official forums (source) has given us all a way to better monitor your online ping. Here is her technique:
Navigate to the folder: 'program files\steam\steamapps\common\call of duty modern warfare 2\players' and open the file config_mp.cfg
Change scoresping_interval from 100 to 20, and maxbars from 4 to 10 (10 is the max).
This means that each of the 10 bars represents 20ms, with full green being 20ms or lower, and 1 red being 200ms or higher.
WHAT IT LOOKS LIKE:

MW2: Online ping monitoring