From what I've seen you need to do it one of these ways ...
1) Have some software running on your own web server (you host your own website).
2) Use some ActiveX applications on your own server if Windows.
3) Use an outside (remote) service.
So the answer is no ... you can't just use PHP to create a thumbnail
from a URL. At least I have never seen a way to do it.
I also checked with Perl ... same thing. You need your own server.