I have noticed that emacs w3m does not work in F20 alpha. Emacs version is 24.3.1, emacs-w3m-el 1.4.435 and w3m 0.5.3.
I found a post regarding this (Debian?) http://emacs-w3m.namazu.org/ml/msg11934.html which indicates the issue is likely related to the versions.
"Upgrading emacs-w3m to 1.4.483 or later may prevent this problem."
I haven't had time to test this myself yet, as I am configuring stumpwm (maybe an idea for the repos?).
All the best,
Johnny