SY talked about the soundtracks box in an interview in the Wire (2004?).
On Thurston's atp (2006) Steve told Sonicl and me that they are working on it. The last I heard is when they said they are not sure whether it will be a box or separate cds. Unfortunately I have no other info about any other SYR.
You can post your wish here:
http://www.sonicyouth.com/gossip/showthread.php?t=23968

Absolutly awesome cover art. It'll be more awesome if someone shows it to the band! Congrats.

ok thanks my man, this is some vintage "info" from the band themselves. I'd be stunned if the released a SYR box, yo

Oh gosh I thought I was still in the sextape thread and when I saw Moshe message I thought "wtf it's going to happen"

perv.