[rshao]

You would just have to assess your target audience and decide whether the cost of developing support for OpenID are outweighed by the benefits of allowing a portion of your users the convenience.

I see little reason to implement it if your most of your users will be unaware of it. On the other hand though, having the support for it (and similar providers) may help you attract those users who do use them. If you do implement support though, make sure it doesn't obfuscate your registration and login processes.