Update (2 days later): SixApart’s CEO Barak Berkowitz provides more details. He posted his Message from the CEO to the TypePad blog and also sent it in an HTML email to customers:

Dear Debbie,  

As you might know, some of our users have been experiencing slow performance with the TypePad service over the past few weeks…

Pretty nice. To back up a minute… we (meaning a bunch of contributors to this blog) are taking partial credit for these blogged
responses from SixApart. We started complaining vociferously on
Wednesday Oct. 26th (first me and then Tris Hussey, Rich Brooks, Toby Bloomberg and Paul Chaney) about the recent slowness and outages with TypePad, SixApart’s popular hosted blogging service.

The result? SixApart co-founders Mena and Ben Trott posted a reponse,
the first real explanation we’ve gotten from the company after several
weeks of problems with TypePad. The number of TypePad blogs and the
activity on them (the good news) has outstripped their server capacity
(the bad news), they tell us. They’re working to move TypePad to a new
data center (which hasn’t been going smoothly).

Moral of the story? The blogosphere works. You kvetch enough. You get everybody’s attention. (Addendum: we’re quite pleased with the effect of our buzz campaign.) Now let’s  hope they can fix the problems…

Backstory
I sent Anil Dash
(a SixApart VP) several emails yesterday begging him to "listen up" and
to make lemonade out of lemons, so to speak. Anil is a friend and
colleague. I suggested he get the top dogs at 6A to acknowledge the
recent problems and address them more transparently than the cryptic
messages we get on 6A’s Status Weblog about "temporary service degradation."

He listened.

Another
takeaway… there are many channels of communication. You need to use a
combination of public and private ones. The blogosphere is a very very
public place. It’s not right for everything.