It also crashes if you put almost any other character after the $

shell> perldoc -q '$_'
Segmentation fault (core dumped)
shell> perldoc -q '$='
Segmentation fault (core dumped)
shell> perldoc -q '$p'
Segmentation fault (core dumped)
[download]

But I've found * and + to 'work' (see. not core dump ;-)

broquaint

Update:

Having just compiled up v5.7.2 I find this bug has gone (at least on my system), and upon doing a diff on the 2 versions' regexec.c I get a rather significant amount of changes (2599 according to wc -l).
Many thanks to those (rinceWind, Chmrr, Veachian64) that have tested so far!