I tried out the site you mentioned and if the server wasn't outright lying to me this is what I got via Fiddler2:
Server: Apache/2.2.16 (Unix)
mod_ssl/2.2.16 OpenSSL/0.9.8e-fips-rhel5
mod_auth_passthrough/2.1
mod_bwlimited/1.4
FrontPage/5.0.2.2635
mod_perl/2.0.4 Perl/v5.8.8
From this I could assume that the website is run via perl CGI scripts running on an Apache webserver under Unix, but then again why should I trust what some webserver tells me. :-D
As has been said before me, it is impossible to say even when file extensions .aspx .ashx .pl and .php or whatever are present it doesn't mean a thing.
Cheers!
Manfred