It's an odd case: potentially a good effort, deep backing by all the right groups, but it had some weird techno-political isse (Rob Reiner's involvement with a state comission AND this effort) and sort of dropped off the radar and then lost. Who knows why these things happen, but some analysis I've seen is that it was too much of a narrow bullet: people said "If you can raise all that money [1.7% of incomes over $400k/$800k], the schools need much more radical reform first" ...
Plus there's the perceived 'problem' of giving a handout to those who can already afford preschool. Is it really that hard to administer a needs test for things like this? "It's $8k/yr, get up to 100% off by showing your AGI from last year's 1040"
/jordan