See here.

One option is Cecidomyia piniinopis, the gouty pitch midge, whose larva Packard says "fastens itself to a pine leaf and remains motionless until the resinous exudation resulting from its attacks hardens, forming a cocoon-like pupa case or puparium." But since the Forestry Images page just gives the genus, I presume there are other possibilities.

Moved from Dark-winged Fungus Gnats.

Based on the image of the eclosed adult clearly a cecidomyiid (note wing venation), either Porricondylinae or Cecidomyiinae. Nice series of biological images!

Moved from Sawflies, Horntails, and Wood Wasps.

I just wanted to point out that these cocoon pictures are incorrectly filed under sawflies etc.
I just read in this book that fungus gnat "pupation takes place mostly in delicate cocoons and a few are suspended by some loose silk from the surface of fungi or other objects." I've seen a couple of other vague references to this, but it's nice to see actual photos of what this looks like!

It just hatched or popped out or whatever. It's a fungus fly of some kind. I'll try to get shots later today.

My guess would be a cocoon. For one thing, eggs are hardly, if ever, oriented horizontally to the substrate (ok, Microcentrum katydids being an obvious exception).