Talbin,
FUE merely moves the hair follicle from one part of your scalp (back) and replaces it in another part of your scalp (front).
The harvested areas will not regrow, since the follicles are no longer there. However, because of the directional growth of the hair at the back of your head, you can harvest a fair amount of hairs with FUE without losing any apparent density in the donor area.
There is another procedure known as FM (folliucular multiplication). I have read about it on Hairlosshelp previously, where someone was saying they had had it done. With FM, *apparently* half the follicle is removed, so that both the harvest area and the target area regrow hair.
This second procedure sounds bizarre and pretty much impossible to me though. Then again, I have not really researched it too thoroughly. It is more expensive than FUE.