GNOME 2.2 officially incorporates the Metacity window manager, a fully integrated window manager that uses GTK+ for UI elements, communicates tightly with the panel and other desktop elements, and is configured straight from the GNOME preferences dialogs.
At the same time, all interaction between the window manager and the desktop is done via documented standards (see the section called "Standards Compliance"), so you can substitute the window manager of your choice from a long list of available options: Sawfish, fvwm2, icewm, Waimea, Openbox, are just some of them.
Early versions of Metacity were in wide use a month or two after GNOME 2.0, so many people will already be familiar with its basic features:
Does not expose the concept of "window manager" to the user. For example, keybindings are configured in the GNOME "Keybindings" dialog, theme is configured in the GNOME "Theme" dialog.
Simple XML theme format is designed to allow a single theme to work with large and small font sizes, button reordering, and other user preferences. No more editing the theme to change your preferences.
Like all of GNOME, full keyboard navigation, including navigation to the panel and the desktop background.
Inherits the standard GTK+ internationalization support.
Uses GTK+ to draw window frames, tracking colors, fonts, and so forth from the GTK+ theme. (Colors may not be tracked by all Metacity themes, but any Metacity theme can choose to do so.)
Some new features that may not be in the version of Metacity you've tried before:
Themeable icons in the window menu.
Handles dynamic resolution changes via Xrandr extension.
Supports keybindings with <Super>, <Hyper> and <Meta> keys. (Including Windows logo key.)
Supports stay-on-top and stay-below hints.
Allows window buttons to be rearranged (close button on left, etc.), as a user preference, not part of the theme.
Better multihead support.
Startup notification support.
Numerous performance optimizations, especially for high-latency connections.
Numerous bug fixes and behavior tweaks.