Hello,
compiling a LuaLaTeX document with rev. 20998 of expl3 results in the error:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! 
! This is a LaTeX bug: check coding!
! 
! Command `\lua_shipout_x:n' not yet defined!
! 
! See the LaTeX3 documentation for further information.
! For immediate help type H <return>.
!...............................................  
                                                  
l.68 \cs_generate_variant:Nn \lua_shipout_x:n
                                              { x }

in the file l3luatex.sty; probably because \latelua is not enabled by default.

Regards,
Philipp