@Openavatar: Yes, you are right, sadly the most OpenID plugins and Profiders doesn't support the AX Image, but if the do so please support it.
The main problem I have with Openavatar is, that I don't want my OpenID to be displayed in the URL field. My OpenID is only to authenticate my profile data. After authentication, I want my (in the OpenID profile defined) blog or website url to be displayed. The WP-OpenID plugin doesn't support that completely, thats true, but I hope they will do it in the near future.
I could work around that problem if I would use the openid.delegetion in my blog, but its very uncomfortable because I have to upload a new Image, I have to change my Blog Template (OpenID delegation and openavatar functions) and I have to install your Plugin.

The advantage of Gravatar is, that it works with every E-Mail - Address (you support only OpenID urls instead of any kind of url) and it is a core part of WordPress 2.5.