just upgraded to jaunty, and things are as follows:
1) Firefox + gnome-support: opening remote files through nautilus (double click) works; opening through command line (firefox smb://share/file.ext) doesn't work; opening with location bar doesn't work. In the last two cases, since in my case we work in a MS Active Directory environment no password dialog is presented;
2) Firefox file selector doesn't lists network folder (this is the reason why I opened this bug report);
3) Open files thru folders in ~/.gvfs works, and save file works too.