As Geoff says here, support for MyOpenId has not been removed altogether, although they have been demoted from "recommended" or "featured" provider status due in large part to the problems that many of their users have experienced when trying to log into our site recently.
Now, instead of having a large button to click, you have to click a smaller one. It still has the MyOpenId logo, so it should still be easy to find, but it doesn't look quite as inviting.
We do highly recommend that you add an alternative OpenID provider (remember, an account can have multiple associated login methods), just in case something goes wrong with MyOpenId and you're unable to log in to the Stack Exchange network. The Stack Exchange OpenID provider, Google, or Facebook are all great choices. For help, see this entry in the FAQ.
And perhaps a hint that mysql is slow and patience is required.
I don't see why this is necessary. The "hint" is that we've demoted them from favored status. Anyone who continues to use MyOpenId is going to be aware of the potential problems, and therefore would find a pop-up hint each time annoying.