There have been many occasions when the large players like MS or Google announced something and nothing usable came of it: e.g. OpenSocial is mostly vaporware.

There have been many occasions when the large players like MS or Google announced something and nothing usable came of it: e.g. OpenSocial is mostly vaporware. Also, Google AND Yahoo, i.e. two huge corporations working together raises flags for me. When's the last time that worked out? There'll be a lot of managarial communication, overhead, bureaucracy, stupidity, etc. Assuming they really are doing this together: having worked at large corporations and knowing how inefficient even internal management is, I actually wouldn't worry too much about this.