Apache proxyPassReverse and Websockets
In March a patch was committed to the Apache trunk by Jim Jagielski which allows websockets to be proxied correctly. The patch adds a new submodule called proxy_wstunnel which allows mod_proxy to work with the "ws" and "wss" protocols.
The module is not yet in any official Apache releases (as of June 8th 2013), so you will need to compile it yourself. Voyageur's blog describes the process for Apache 2.2, but it should be easier for Apache 2.4