/test/js/ directory. It needs someone to go build a web browser implementation. Bonus points if it utilizes WebCrypto!
Why haven’t we done it yet? It’s simple, really: there’s only a handful of us working on the project, and it’s pretty hard to build a publicly-trusted CA. It’s not like this is a well-funded startup, hiring 50 people. It’s a not-for-profit focusing on making the core, hard bit, while providing the tools needed to extend it – ACME.
I, for one, look forward to a simple browser implementation of the manual process as well.
(I, for one, also look forward to things like weekends again.)
The ACME spec doesn’t support wildcards. Let’s Encrypt, being the first CA to implement ACME, won’t support them until ACME supports them. If anyone reading this is really interested in solving the apex problem, and the other thorny bits, please join the ACME IETF mailing list and help work it out.