This occurs when drum and bass/dubstep (and probably other types of dance music) producers bring out a different version of the same track. The purpose is to surprise the crowd with something different but memorable. Usually only tracks that were originally popular get the VIP treatment.
It is not the same as a remix, which changes the original track quite significantly, sometimes only keeping a few elements of the original song. Quite often remixes are a different genre entirely.
A lot of VIPs are never released commercially, and are instead given solely to DJs to play out.
Used in electronic music (such as drum and bass or breakbeat) when a producer remixes their own track. A VIP uses major elements of the original version but differentiates the track as a whole.
1) I'm going to be in the VIP area.
2) "Red Mist VIP" by DannyByrd is sick! It's perhaps even better than the original.