Tammy here. I think I have what you wanted. I created A fading trail on a bullet mesh (like in The Matrix). The trail is also a mesh. Actually it's a bunch of duplicates of the bullet mesh. Here's how I made it in Maya 8.0:

The bullet:
I made a sphere, deleted the bottom half faces, and extruded the bottom edges outwards. I extuded the same edges again, and scaled them inwards (without moving them), for the flat bottom of the bullet.

The trail:
Duplicate the bullet mesh seven times, and move each duplicate behind the other, and overlap them a little. Create a slightly transparent material in hypershade, and apply it to all the trail mesh pieces. Select the transparent material, and click Edit>Duplicate>Shading Network in Hypershade (do that two times). Make each trasparent material slightly more transparent than the other. Select three of the trail pieces, and click Mesh> Combine in the polygon menu set. Select the next two pieces and combine them also. Select the last two and combine them too.

To animate the trail:
Make sure AutoKeyframe is off. Select the bullet and all the trail pieces. Press s to set a keyframe on frame 1. Go to frame 3, and move the bullet and trail forward a little, and then press s.

Repeat the process in the last sentence for frames 5,7,9, and 10.

To animate the trail transparency:
At frame 3,make the material for the first three trail pieces slightly more transparent. Right click on the transparency color box, and click set key.

Repeat for the next two trail pieces, and the last two.

Repeat the entire transparency animation process for frames 5,7,9, and 10.

I have a zip file included here. It has a mini video of my matrix bullet trails in .avi format:


I hope you enjoy this!
- Tammy