I see, perhaps the tx sequences and nLockTime already let you do these things.  I do not quite understand the sequence/nLockTime semantics, are they explained clearly somewhere you can link me?  And are you sure they are actually working now?  I thought I had read the "lock time" thing was disabled, and I remember reading the source a few months ago and seeing weird stuff like "non-simple" tx scripts containing more than 2 ops were disabled.

i forgot PW to first account and it's not sending me email... mods pls unnoob this account instead of OP (you can check IP match).

bitlotto: AFAIK you can't condition on block number either in tx scripts.  Either would be fine I guess actually, could be nice to have both.