The PICkit2 is now "static".
No new parts are being added to it.

Already, there are many parts that the PICkit2 cannot program.
All new devices are only added to the PICkit 3.

If you are buying one now, get the PICkit 3.

I have a PICkit 2, PICkit 3, ICD 3 and melabs U2 on my desk.
Only the U2 is ever used. With the exception of troubleshooting for someone else that is using a PICkit.