As I understand it, yes! I remember reading about this a while ago (possibly here on PPrune).
There are a number of microswitches in the gear oleos which let the aircraft "know" when it is on the ground. i.e. select between 'ground' and 'air' mode.
For some aircraft (and those who fly them can fill in the gaps :-) reverse thrust can be deployed after x seconds when both mains are 'on' or 'y' seconds if one main + the nosewheel are 'on'.
Sorry I can't give a more technical answer, but this at least gives you an idea of how it works.
Regards,
Shuttlebus
P.S. Wasn't there an accident in the US with a DC-9 when an under-inflated nose oleo led to the aircraft (and crew) becoming confused - since some fuctions did not change over from 'ground' to 'air' (Probably an NTSB report)