As you may have noticed, these man pages were made by Sun for for Solaris, so Ubuntu cannot simply copy them due to copyright restrictions. The solution is for upstream (in this case, Gnome) to create the man pages themselves.
And, as already pointed out in the comments, this was requested via bug reports in both Ubuntu and Debian circa 2008. There were also many bugs filed directly upstream about this issue.
I personally filed a request to Gnome in 2011, and attached the *.1.gz man pages files from Solaris as a suggestion. They were not directly used (for technical reasons), but a few months later they created and included the man pages for all gvfs commands.
The upstream git commit including the man pages is quite recent, from June/2012 (and a few more included and then polished in August/2012), thus after Ubuntu 12.04 Precise was released.
Then, both Ubuntu and Debian must wait for a new upstream version to be released after. That only happened in 2012-07-16 in gvfs 1.13.3 and 2012-08-12 in gvfs 1.13.5.
But gvfs in Ubuntu 12.10 Quantal is currently at 1.13.7, so the man pages are there in
See, the system works ;-)