If not mistaken a gap generator is like a stealthing tower, it just makes a big black mark on ur enemy radar over the tower and its surroundings.
Btw, just started playing C&C Tiberium Wars.
Let me tell you, C&C has come a long way with this one, still using famous actors for the movies thos. Dono about the pr0n stars this time.
Lots of new units, with some old favorites like the mamoth tank coming back.
All units come in groups now, so insted of buying one G.I you buy a lil squad of 5.
Now its not countries agains countries. Its G.D.I vs N.O.D (From the Renegade series). However, there is also a new race, the Scrin. Which is like aliens.
The U.I has changed, allowing for multiple build lines. Even for buildings.
In Skirmish, there isnt that many maps at the moment.
Couple of pictures:
http://gamereplays.org/cnc3/images/cnc3_screen0072.jpg <--- Big
The forces on the left are G.D.I the ones on the right are Scrin