This blog is updated daily..
A general description is here.
HTML help is now generated dynamically using a http server running in the R process and listening on the loopback connection.
- the implementation is currently incomplete, for example browsing vignette directories is only minimally implemented and not much error reporting is in place.
- those who need to worry about security implications of such a server should not use HTML help until more security measures are in place -- the server is started at first use.