A variable readable at run time that automatically increments every time PBP is invoked (a BYTE for some, a LONG for a few of us).
PBP might have an .ini file that would match the .pbp filename and keep various PBP parameters in there along with the version count.
Then at run time, something like this happens:

Code:
version_variable var WORD 'or BYTE or LONG or whatever

main:
version_variable = pbpversion
lcdout "Current Version is : " , DEC5 version_variable
end
If nothing else, it might be kinda fun to see how many times a guy compiles a certain program just to see how many times you program a particular PIC.