Thanks for pointing that out, but it suffers a few issues I don't like:
1) It puts each frame on a layer instead of laying them out in a sheet.
2) They, too, have to use a new extension "agif". This may not be solvable, though.
If I can't solve the second, then I guess I'll just have to deal with it, but I definitely prefer animation strips over using layers as frames. Personal preference, I suppose.
So back to the issue at hand, anyone know of a way to get Paint.NET to use my plugin for a GIF file or am I forced to use a different extension?