My Xperia Arc just got the update to the latest Android Market.
The Market did update automatically, it just needed longer to start, because of that I opened the new text message that I had and afterwards the new market was there.
It works quite fast and fluent on the Arc.
But the old market was faster and I have to say that I liked the old market more. But maybe that will change after I used the new marekt for some time.
I don't know if the other Xperias got the update, too, but if not they should receive the update soon, too.