Aldabra is a GTK2 theme that uses the Murrine and Pixmap engines to mimic the look of Adwaita, the default GNOME 3 theme.
The goal of this theme is to provide visual consistency between GTK2 and GTK3 applications. It is a work in progress: over the next few days, I hope to add accurate buttons and to fix application-specific issues.
Anyone is welcome to rename, package, or otherwise distribute the theme (in whole or in part). Constructive feedback is greatly appreciated.
Edit: Aldabra is now available on GNOME-look.org.