Upgrade Gnome to 2.16
I upgraded my Gentoo desktop to Gnome 2.16. I really like many of the new features. The Tomboy note taking app is much better than the old sticky notes applet. I also really like the baobab application. It is an app that shows disk usage in a gui. You can drill into folders and find how much disk space it is taking. There were also many changes to some system UI objects like the file browser and printing dialog box. Overall, I recommend the upgrade.
The Gnome package and most of the dependencies are currently masked so you have to unmask many of them to upgrade. You can unmask a package marked testing with the ~x86 flag by adding a line with the full package name to the /etc/portage/package.keywords file.
Example
echo gnome-base/gnome >> /etc/portage/package.keywords
If the package is blocked by package.mask, it can be overridden by adding a line with the full package name to the /etc/portage/package.unmask file.
Example
echo gnome-base/gnome >> /etc/portage/package.unmask
Below is the list of things I had to add to my package.keywords
gnome-base/gnome
dev-libs/atk
gnome-base/libbonobo
app-text/evince
gnome-base/gnome-applets
x11-libs/libxklavier
x11-themes/gnome-icon-theme
x11-misc/icon-naming-utils
app-editors/gedit
dev-libs/glib
dev-python/gnome-python-desktop
gnome-extra/nautilus-cd-burner
gnome-base/nautilus
gnome-base/eel
x11-libs/gtk+
x11-libs/cairo
x11-libs/libwnck
x11-wm/metacity
gnome-base/gnome-keyring
dev-python/pygtk
dev-python/pygobject
x11-libs/gtksourceview
gnome-base/libgnomeui
gnome-extra/gcalctool
x11-themes/gtk-engines
gnome-base/librsvg
media-video/totem
x11-misc/alacarte
gnome-base/gnome-menus
net-analyzer/gnome-nettool
gnome-base/gnome-panel
media-sound/sound-juicer
app-admin/sabayon
gnome-extra/gconf-editor
gnome-extra/zenity
gnome-base/gdm
x11-terms/gnome-terminal
x11-libs/vte
gnome-base/gnome-session
gnome-base/control-center
gnome-extra/evolution-data-server
mail-client/evolution
net-libs/libsoup
app-arch/file-roller
gnome-extra/gnome-power-manager
gnome-extra/fast-user-switch-applet
gnome-extra/gucharmap
gnome-extra/gtkhtml
gnome-extra/evolution-webcal
gnome-base/libbonoboui
x11-themes/gnome-backgrounds
gnome-extra/gnome-utils
www-client/epiphany
x11-libs/pango
gnome-extra/gnome2-user-docs
gnome-base/libglade
net-print/gnome-cups-manager
gnome-base/gnome-vfs-monikers
gnome-extra/yelp
gnome-base/gnome-desktop
gnome-extra/bug-buddy
gnome-base/libgtop
gnome-base/libgnome
dev-libs/libIDL
x11-themes/gnome-themes
gnome-extra/gnome-media
media-gfx/eog
gnome-base/orbit
app-admin/pessulus
gnome-extra/gnome-keyring-manager
gnome-extra/deskbar-applet
gnome-extra/gnome-games
gnome-extra/gnome-system-monitor
Below is the list of things I had to add to my package.unmask
gnome-base/gnome
gnome-base/libbonobo
gnome-base/gnome-applets
x11-libs/libxklavier
x11-themes/gnome-icon-theme
x11-misc/icon-naming-utils
gnome-base/gnome-vfs
app-editors/gedit
dev-libs/glib
dev-python/gnome-python-desktop
gnome-extra/nautilus-cd-burner
gnome-base/nautilus
gnome-base/eel
x11-libs/gtk+
x11-libs/libwnck
x11-wm/metacity
gnome-base/gnome-keyring
dev-python/pygtk
dev-python/pygobject
x11-libs/gtksourceview
gnome-base/libgnomeui
gnome-extra/gcalctool
x11-themes/gtk-engines
gnome-base/librsvg
media-video/totem
x11-misc/alacarte
gnome-base/gnome-menus
net-analyzer/gnome-nettool
gnome-base/gnome-panel
media-sound/sound-juicer
app-admin/sabayon
gnome-extra/gconf-editor
gnome-extra/zenity
gnome-base/gdm
x11-terms/gnome-terminal
x11-libs/vte
gnome-base/gnome-session
gnome-base/control-center
gnome-extra/evolution-data-server
mail-client/evolution
net-libs/libsoup
app-arch/file-roller
gnome-extra/gnome-power-manager
gnome-extra/fast-user-switch-applet
gnome-extra/gucharmap
gnome-extra/gtkhtml
gnome-extra/evolution-webcal
gnome-base/libbonoboui
x11-themes/gnome-backgrounds
gnome-extra/gnome-utils
www-client/epiphany
x11-libs/pango
gnome-extra/gnome2-user-docs
gnome-base/gnome-vfs-monikers
gnome-extra/yelp
gnome-base/gnome-desktop
gnome-extra/bug-buddy
gnome-base/libgnome
x11-themes/gnome-themes
gnome-extra/gnome-media
media-gfx/eog
gnome-base/orbit
app-admin/pessulus
gnome-extra/gnome-keyring-manager
gnome-extra/deskbar-applet
gnome-extra/gnome-games
gnome-extra/gnome-system-monitor
I am sure the list will change but this should get you started.
After completing the upgrade I recommend a restart of the computer to make sure all the new versions of the apps are running. I had issues trying to get by without a restart.