It's so they make sure it's a very polished service by the time it gets on Google Apps.
The changes seem to be up for my Google Apps account. Investigate your site settings panel.
Tell you what: when we expand the field trial to include Apps users, and I get some invites, I'll hand extras out to HN readers with Apps accounts. If you fit this description, write to me on reddit:
What happens when you visit http://plus.google.com/ ?
But my world depends on my primary email. I get notifications on my phone from it. I have my calendar, my Picassa, my documents on it and I also use Google Talk quite a lot lately.
And because I did the recent migration, I cannot have a parallel regular Google account tied to this email address; it used to work fine this why with some minor pitfalls.
If you don't have a Google Apps account that you really depend on, you can't feel the same pain I do :)
Surely they'll promise availability in a month from now or so, but it's going to take several months or years anyway.