(Some of the following notes surely apply to bash, don't know about other shells).

You can use the backtick operator or its equivalent (and prefearable, IMHO):

return1=`/path/to/script.pl arg1 arg2`
return2=$(/path/to/script.pl arg1 arg2)
[download]

The latter has the added advantage of allowing nested subshell invocations.

If your return value can have newlines, I'd suggest to use double quotes:

return_newlines="$(/path/to/script.pl arg1 arg2)"
[download]

And yes, you can use read as well, but you have to be extremely careful about what you want to do. Suppose you have the following script:

#!/usr/bin/perl
print $_, $/ for @ARGV;
[download]

and you want to set the variable value to the contents of the last line:

#!/bin/bash
value=0
echo "value starts from $value"
./script.pl arg1 arg2 | while read line ; do
   value=$line
        echo "value is $value"
done
echo "after first while, value is $value"
 
while read line ; do
   value=$line
        echo "value is $value"
done <<<"$(./script.pl arg1 arg2)"
echo "finally, value is $value"
[download]

you obtain:

value starts from 0
value is arg1
value is arg2
after first while, value is 0
value is arg1
value is arg2
finally, value is arg2
[download]

Note that after the first while the variable value has not been modified. This is due to the fact that the first while cycle is being executed inside a subshell.

OTOH, the second while is executed directly by the "current" shell. This may lead to problems if you pass a lot of data back, anyway.

Note that there are also other ways, but there is too little space on the side of this post to write them.