I think I might be re-challenging myself because I've finished the first skein for Le Tour de Fleece.
The pink yarn I used to tie the skein is 4ply so a rough and ready comparison suggests I'm reasonably on target for sock weight yarn. Its not all the same thickness though! But my consistency isn't too bad. Practice will make it even better.
A pic taken with the flash can be seen here.
Its going to be one bright pair of socks!