There is an open protocol[1] on how to retrieve the certificates, so you can implement a client in a language of your choice, or wait until someone else does it.
Re:Intent to deprecate: Insecure HTTP
by yellowapple on Tuesday April 14, 2015 @10:04PM
(#9378503)
That comment was about package management (i.e. actually installing this on servers), not about language implementations. Let's Encrypt's documentation currently assumes a Debian-based operating system, which therefore leaves out a very large portion of the web server population.
[1]: https://letsencrypt.org/howitworks/