If its a Draytek (for example) with Dynamic DNS configured, then the iPad can open a PPTP or IPsec VPN to the router from the public WiFi and that will encrypt the connection over the public WiFi.
I do the same, but I have a hosted server, rather than using my home broadband.
James be* pro (16.8 / 1.2 sync) -
BQM - FTTC cab installed 18-jun-2012 -
not yet active - est 44.6 / 6.5