bash allows this:

perl test.pl & jobs -nl > out.txt

out.txt will contain a line like:

[2]+ 27872 Running     perl test.pl &

You can call it from Perl using (untested) (see update):

open (FILE, "perl test.pl & jobs -nl |");

update: I had to use this in order to make it work:

 open (FILE, "perl test.pl & jobs -nl | cat |");

update: don't use this. It is not portable. Use fork instead - see below.