Yep…for this reason I actually set up two tunnels on port 443, one using UDP and the other with TCP, and have both configured in my OpenVPN client. I suspect, though I don't use free wifi very often, that many providers are sloppy and if they do lockdown ports, may allow UDP and TCP both on port 443, so the UDP version would still be usable. However, TCP is still available to fall back on.
But, another issue might be if they are examining all port 443 TCP traffic for content filtering...on corporate network this is done by pushing a trusted root certificate from the firewall to all company-owned machines and generating spoofed certificates for every secure site so the firewall an inspect and transparently proxy the traffic. I've seen public wireless misconfigured (intentionally?) to do this as well, though you will always see a certificate warning unless you manually install their root certificate (not recommended of course). However, it may prevent access via port 443 TCP using OpenVPN (though UDP could be blocked in any of the above cases regardless).
Assuming DNS is not blocked/proxied, you could fall back on using TCP-over-DNS for remote communication, but that has nothing to do with pfSense (though it would be cool if someone wrote a pfSense package for it :-) Or, find another Internet connection to use, which may be the easiest if the network really is this locked down.
