I like FunkyMonk's solution, but here's another:

if ($time =~ /^\w{3}\s\d{2}\,\s\d{4}(\s\d{2}:\d{2}\s\w{2})?/){
    print "Found it\n";
}
[download]

I'm new to regex too, but I thought I'd give a crack at it too.
Cheers!