I have noticed that the Meffert's site have been
down for a week with the message that they are
upgrading their system.

Does anybody know what's happened to Meffert's site? It's been down for a few weeks, and I'm beginning to wonder if it'll be back or not.

The Meffert site was down for I don't know how long (I honestly don't know, as I hadn't checked it for a while when I found out), but is now back online, and has been so for the last two or three weeks.
The urls are (as if you didn't know):
http://www.mefferts.com
or
http://www.mefferts-puzzles.com

If you can't get to the site I really don't know what to tell you, 'cause it works just fine for me.

I just checked and
http://www.mefferts-puzzles.com --- is up but

http://www.mefferts.com --- is down

Thanks for the tip. http://www.mefferts is actually still down for whatever reason, and that's the address I had bookmarked. The http://www.mefferts-puzzles is indeed working.

On another note, does anyone know when Meffert plans on actually selling the Skewb Ultimate?

They try really hard at that site and they are very honest. It may take some time to get your puzzle but they will promptly answer your inquires. The last time I corresponded with them, Uwe or whoever answer my email told me that they would be available in June. I take that to be soon.

I just got a reply from the Meffert's saying that the Skewb Ultimate won't be available on the site until early July, so about a month away still.

You are right about them trying hard and being honest. They really are very pleasant to deal with.