What I don't understand is why did they create a separate site per topic. With separate user account! This is very inconvenient and complicates things for the users. having it as a 'category' within the same site would be much better for usability (and for SEO :)

As they all use OpenID, the accounts can be the same if desired -- but they've managed to keep the reputation scores separate. To the extent the same person might be motivated to repeat their 'achievements' at each site, this might accelerate the creation of answer content.

Also, this might better yield three distinct communities, each with slightly different norms and leaders, than trying to make one mega-community. The mental styles of programmers, sysadmins, and power-users are different; there's no reason to think the three communities will evolve better if merged. (Scale is not always a benefit in online communities.)

They're not (and can't) relying on OpenID alone for matching accounts on different sites due to the fact that Google and some other OpenID providers generate a different ID for different hostnames, even for the same user.

Aha; good point that I'd overlooked. Is there a way the user could prove the different synthesized IDs are the same Google principal, by conscious choice?

They associate the multiple google id's with each other, so it appears you are using the same one.

AFAIK, you can use the same account on all websites related to StackOverflow (ServerFault etc.). Isn't this the case with SuperUser?

Love the idea and hope it goes well. I can't see myself using it until that horrid bogey yellow is changed though!

Also the rounded rectangles for the tags drive me crazy.

I thought that I liked their graphics designer, as I liked the visual appeal of both stackoverflow and serverfault. Now it feels like they did not pick the right combination on http://kuler.adobe.com/ this time :)

Add in that the color for tags and the title is nearly the same. And the more views the more of a "warning color" the count gets. Seems rather opposite.

It's verging on baby-diarrhea color :/ Nausea inducing.

Jeff is an amazing guy. But, he clearly does not value design.

The design on Stack Overflow is pretty good: minimal, simple, doesn't get in the way. I believe they hired it out to a 3rd party.

However, the color schemes on all the other sites, just aren't quite as good, superuser being the worst. Amazing what difference just a little bit of color makes. The logo on Superuser looks a little amateur in my opinion too, especially considering the other ones that were submitted.

Not necessarily true. He may just be prioritizing releasing new functionality and sites over improving the design for now.

How is this for power users? it looks the same to me.

From the About page: Super User is a Q&A site for computer enthusiasts

It's the same text like on StackOverflow.

I too do not see any "super" difference in the content.

note: If you're already a StackOverflow user, you can bootstrap your account with some reputation points by associating your Super User account with your StackOverflow account.

Most of the entries on that site seem to be about Windows/Macs.

Anyone know of a similar Linux/UNIX-themed site?

Yes, superuser.com.

Seriously, it just opened. Go post some Linux/UNIX themed questions!