Jabber behind corporate firewall at 443

Maybe everyone know it. Until recently I had open all ports to the Internet so I used 5222 and 5223. But now I'm behind some rude firewall. I realized that both Jabber servers I'm using are listening also on port 443! This is conn443.netlab.cz:443 for jabber.cz and talk.google.com:443 for GTalk. So, I'm online again.