Apps as nautilus, system settings, etc...
It's hard to know, but it's likely that you are right.
Bits of the GNOME 3 stack will make their way into 11.04, but a lot of the core libraries and hence many of the updated programs+utilities aren't going to be in 11.04.
It's quite normal for parts of the GNOME stack to be a release or so behind in Ubuntu, and considering the magnitude of the changes in GNOME 3 (the libraries have changed a lot; it's not just GNOME Shell) then it's not surprising that it's the case this time.
I'd except far more GNOME 3 goodness to make it's way into 11.10.
Ubuntu will continue to be based on Gnome, the only difference will be the shell (unity instead of gnome-shell) and the window manager (compiz instead of mutter), and in the future the graphics server (wayland instead of x window system).