First let me just say that I'm as Pro-OpenId as someone could get. Were I king of the world every web site would be required to submit to OpenId and that would be the end of it. That said, I'm not sure that Yahoo adopting it is that big a deal. I quote from a post by Caroline McCarthy of CNet's "The Social"...
In one of the most significant moves yet in the growing push toward service interoperability on the Web, tech giant Yahoo announced Thursday that it is supporting the OpenID 2.0 standard for a universal Internet log-in.
No matter what your views of Yahoo's current stability may be, this is undoubtedly a big victory for OpenID. Not so long ago, the protocol was considered a dot-com/futurist pipe dream. OpenID was created by Web 2.0 guru Brad Fitzpatrick, who founded LiveJournal and was brought on board at Google last year as one of the most prominent players in its OpenSocial developer initiative.
Well...maybe...but I can't help but think our views of Yahoo's health are very relevant here.
I applaud a lot of what Yahoo has done over the past couple years but the reality is Yahoo has been trying to embrace Web 2.0 as a way to pull itself out of a downward spiral. They can claim massive user numbers all they want but that doesn't mean all those people are actively using their services and we all know it.
In the end Yahoo is a company that thinks embracing this will draw customers to them while OpenId needs to woo the companies who already have those customers. So Yahoo adopting OpenId is great but not all that helpful in terms of OpenId's eventual goal of massive adoption.
This brings me to a point I've made before which is that these initiatives have to find a way to make switching profitable for successful companies.
In order to get those companies to adopt an open standard you have to understand their perspective which is that they are having to give up a very valuable lock-in to adopt this. Someone has to come up with an argument that shows them their gain will be more than their loss. I'm not yet sure what that argument is but I think it is key in getting open standards like this adopted by the majority of companies.