What's a production programmer for PIC
Microchip's "production programmer" distinction is largely only meaningful for old chips.  The old flash parts, like the 16F877 for example, had to be checked at both Vdd limits after programming.  Microchip defined such programmers as "production".  Note that this required the programmer to have variable Vdd.

Microchip dropped the double verify requirement in newer chips a long time ago, and there is no mention of a "production" programming algorithm versus "development" in any of these newer programming specs.

Today I am not aware of any official requirement for a "production" versus "development" programmer.  As far as I can tell, this is purely a marketing distinction for newer parts.  They don't want people buying a bunch of PicKit2 for programming in production when their other programmers are more robust (less technical support required) and have a higher profit margin.

To be fair, it really isn't a good idea to use a PicKit2 in production where you need to rely on it.  It has lower drive levels and the design was optimized for low cost at the expense of robustness and accuracy.  However, the "production" distinction is rather hollow without a clear spec of what it takes to be a production programmer.

Shameless Plug

My USBProg2 programmer was specifically designed to the production spec for those PIC where there was such a thing.  It has full variable Vdd and Vpp, and verifies at the Vdd limits anyway, even for those parts where Microchip no longer says you need to.  Other than a little extra time, I don't see a drawback.  You can turn off this feature with a command line option if you want to.

Some of the newer 3.3 V parts, like all the 16F1xxx but also some PIC24, dsPIC33, and 18F support a new programming algorithm that no longer requires high voltage on MCLR (Vpp) to enter programming mode.  Instead, you clock in a special 32 bit signature with MCLR held low.  All interactions during programming can be done with signals at Vss or Vdd.  This opens the possibility of a much simplified programmer.  My LProg is such a programmer.  At only $20 or so each, its the cheapest way to set up a bank of programmers for production while maintaining robust operation, if your PIC type supports the low voltage key-entry method.