Humanity verification via Captcha may be useful for first time logon via OpenId to 

avoid OpenId servers running by attackers wanting to flood WebGUI with new accounts

Currently OpenId module expects protocol to be explicitelly entered by user.

So it is a must for now to enter an OpenID looking like:
protocol://user_id.provider_host 

I offer to make protocol part optional, parse OpenID url entered by the user 
and if protocol is absent then default it to http.

In such case  user_id.provider_host would mean http://user_id.provider_host
while  ftp://user_id.provider_host would stay ftp://user_id.provider_host

I can verify that dannymk's implementation works (see reply above). I replied to his post with a patch that helps it be a little more forgiving of the data entry for OpenID URI's.

OpenID is gaining quite a lot of momentum, and it would be great to see it officially supported as an authentication method in WebGUI. 

I'm adding my karma to this with this addition:

danny_mk's OpenID auth module should be updated to use OpenID 2.0 specification: http://openid.net/developers/specs/

At least:

• OpenID Authentication 2.0
• OpenID Attribute Exchange 1.0
• Yadis Discovery Protocol