We're working on an FAQ. This thread has been really helpful in clarifying which Qs are FA :)

With regard to your questions:

> Will it provide wildcard certs?

Not initially, but possibly in a future iteration.

Note that having an automatic CA addresses some of the use cases for wildcard certs. Namely, if you're using a wildcard cert just to avoid having to manage individual certs for foo-1.example.com through foo-N.example.com, you can just have them each automatically get a specific cert.

> How does it auto-renew, does it have to run all the time?

That will depend on the software running on the web server. The current "node-acme" and "lets-encrypt-preview" implementations in the Github repo are examples. Ultimately, in addition to these tools, it would be great to have ACME / LE support built into web server platforms, which are already running all the time.

> Why is the cert for identrustssl not trusted in Chrome or Safari? That doesn't inspire confidence : https://www.identrustssl.com/

I don't know what the story is with that site, but I believe the Let's Encrypt CA will be cross-signed under the same IdenTrust CA that issued the cert for https://letsencrypt.org/. So Let's Encrypt certificates should work wherever that site works (which includes Chrome and Safari, at least on my MacBook).

> Can every CA support issuing certs this way please? :)

I can't speak for other CAs, but we are definitely open to other CAs re-using technologies from Let's Encrypt to automate their operations. It would be even better for them to collaborate in developing the protocol. That's why we wrote ACME up using the IETF's document format, so that it can be developed in the IETF's open process with many stakeholders involved.