I thought I'd mention that Oleg and I just released an updated texinfo.tex which automatically allows breaking inside @url/@uref arguments (after ./?# only -- and only the second of two slashes :).
This should mostly obviate the need for the annoying @/'s that was the only previous method. http://ftp.gnu.org/gnu/texinfo/texinfo.tex It seems browsers already break url's these days, and I don't think it would be good to break url's in Info or the other formats, so no more changes along these lines are planned. Of course, if anyone notices any problems, please report. Karl (Thanks as always, Oleg.)
