New Quiz: "What does this code do?" (1-December-2006)

Hi all!

Well, it's been a while since we had a quiz so here's another what does this 
code do quiz:

{{{{{{
    my (@list) =
    (
        grep { $cgi->param("$prefix$_") }
        map { /^${prefix}(\d+)$/ ? ($1) : () }
        $cgi->param()
    );
}}}}}}

$cgi is a CGI.pm instance. (in case you couldn't guess.)

A friend of mine whose perl is quite rusty had problems understanding this 
code.

What does this code do? And can you guess in what context it was used?

I'll reveal the solution after a 60 hours quota, and until then please send 
them to me in private.

Regards,

	Shlomi Fish

---------------------------------------------------------------------
Shlomi Fish      shlomif-ik1l9ssToec+JF/[email protected]
Homepage:        http://www.shlomifish.org/

Chuck Norris wrote a complete Perl 6 implementation in a day but then
destroyed all evidence with his bare hands, so no one will know his secrets.