There are some community activities to implement client-side encryption. But as far as I know there doesn't exists any running code at the moment. So don't expect to much in the next few months.
In general I want to note that client side encryption is great. I also like and use it in many areas. But you also have to keep in mind that it will make most of the web interface and it features useless. Personally I run my ownCloud in my basement. The connection to the server is secured by https and the hard disc is encrypted with LUKS. In this case it doesn't make sense to me to add additionally server-side or client-side encryption.
The first step is always to check your threat model, your setup and your requirements to see if you really need server-/client-side encryption.
