I came upon this blog entry while using the following search term in Google: "safari openid". I have been using Verign's SeatBelt extension for Firefox to enable OpenID credential entry for some of the OpenID enable web sites I use.
I agree with the author. Entering my OpenID URL ( often quite long ) for each site becomes an annoyance after a while. Google's Blogger has something like this for leaving comments on Blogger hosted blogs.