I believe Will Norris is having a look at this. He’s just completed the OpenID v3 plugin for WPMU, so it’s a matter of porting it to BuddyPress.
good to hear. I will be very interested in having OpenID available. Any chance at a music or video section for buddypress?
Just as a follow up to this, here is the relvant urls:
http://willnorris.com/2008/10/wordpress-openid-v3
https://wordpress.org/extend/plugins/openid/
According to Will, it’s already working in WPMU so we’ll have to look and how to make this work in BP. I’ve got a client interested in this, so hopefully I might report back in the near future.
That’s very good news! Thanks for replying. 
I’m going to be focussed primarily on getting OAuth into WordPress for the next bit, so won’t have a lot of time to look into this myself. If you all find any problems in the plugin that need to be patched in order to work with BP, do let me know. Best bet would be to ping me directly (willnorris.com).
This plugin works with wpmu 2.7 in following steps.
1. user manually registers.
2. activate account
3. go to profile, add openid
4. users can now login with their openid account(s)
OpenID login form is displayed on wp-login.php, but not on buddypress themed wp-signup, as it’s customized for buddypress.
This thread is not updated since 2 months ago, anyone else with tips or updates?
@Takuya, try liaise with Willnorris about adapting it for BP? maybe there’s an OPENID side-bar widget which could used on the BP home theme!
