acroread-7.0.5 has net-print/cups as one of its dependencies, blocking lprng. However, acroread should not impose the use of a specific printing system. In my case, I must have lprng installed since I cannot use cups in our network environment.
Acroread dlopens libcups.so when you open the print dialog and will segfault if it's not found (which is the reason for the dep). I've added a binary libcups.so to 7.0.5-r1 that gets installed with USE="-cups" and the dependancy is now conditional on USE="cups".
