Under the dipples are aluminum rivets that hold the support to the fiberglass. Then they used a body filler over the top of them. Later cars no longer have the rivets for that reason. You will need to remove them and replace them. I believe that the later cars support are just glued together in that area.  

If you're talking about the "bumps" across the nose, behind the headlite openings, it is indeed the rivets popping thru. Bad news is, the only real way to correct the problem is to remove the support, and the bonding strip it is riveted to, and start over. If you just grind it down, and fill the holes, it doesn't stop the rust, and the problem will still be there.
The problem is the rivets rusting. When they rust, it pushes the 'glass up around them, and creates the dimples/bumps. The support that goes across the nose is steel. There is a bonding strip riveted to that, and then the bonding strip is 'glassed on the nose.
I have heard of some people being able to remove the support w/bonding strip from underneath, and repairing it that way. There is a lot of disassembly involved, but...the alternative is to remove the front end from the car.

What about digging out the filler, drilling out the rivet and replacing it with a stainless steel screw?

What filler?? The bonding strip is 'glassed directly to the front nose body. Any hole you drilled to try to repair it would have to be larger than the rivet area, which would mean even more bodywork to fill in those holes!

[QUOTE=Adams' Apple]What filler?? The bonding strip is 'glassed directly to the front nose body. Any hole you drilled to try to repair it would have to be larger than the rivet area, which would mean even more bodywork to fill in those holes![/QUOTE] my7T12006-10-25 06:21:02

Yep...
The corrosion/rust has already started. Sealing won't do anything to help at this point. It may take a while to re-show, or it may show again in a few months...hard to say...