RAM Disk gets unmounted when coming out of sleep
I've similar workflows around a ramdisk so I notice the same issue. I check and re-check the Energy preferences to no avail, so I started messing with the hibernatemode in pmset.

Its default is 3 in Snow Leopard &amp; Lion, and it's not a problem until Lion. Now I've change it to 0. The difference is that no system image is written on disk, so that while sleeping, if my MBP ran out of juice, all will be gone but this drawback is negated by Lion's Resume feature.

Now, it seems my ramdisk stays around during/after sleep... See if you notice similar.