i recently checked out vogueknitting (spr/sum 05?) from the library, which has the lace leaf scarf pattern, which i adooooooooore.
i knitted a couple of repeats with some leftover junk acrylic yarn.
but say i wanted to knit the entire scarf w/ caron simply soft? it’s a 100% acrylic yarn, but feels really nice. i realize that you can’t really block acrylic, but i like how my swatch looks unblocked anyway. (:
but wait, can caron simply soft be blocked? how?
and are there any other problems with knitting lace with acrylic yarn besides that it’s not blockable?
I don’t see a problem with it. I’ve done it with fine results. As long as your stitch pattern isn’t one that curls in a lot at the edges it should be just fine. If you like the yarn and how it feels, go for it! 
Some people who knit lace with acrylic claim to be able to block it using a process that they refer to as “killing” the yarn. As far as I can recall it involves using a really hot iron to basically melt the yarn. Obviously, I have never tried it myself.
I made a lace scarf with Plymouth Encore once which is a mostly acrylic yarn and it looks fine so I wouldn’t worry about it blocking it.