I started working on one back when my Spring Break started, but stopped after World 1 because Sleepz was almost done with his (currently-published) warp run (with tricks that would speed up my WIP by at least 7 seconds).
http://tasvideos.org/forum/viewtopic.php?t=86&postdays=0&postorder=asc&start=180
This is apparently the last WIP I posted:
http://www.kraftfam.org/~erk/nesvideos/smb2.zip
It should finish World 1 unless I'm mistaken. Also, why didn't I continue working on it? Well, between my stopping and Sleepz publishing, there was yet another post at Speed Demos Archive talking about Silent Hill 2-4 runs, and I started working on a Silent Hill 3 speed run. That's my current project.
(Will I start working on SMB2 warpless again? If somebody else doesn't pick it up, I'll probably return to it after the SH3 stuff, but there's no telling when I'll be done with that so...)