Earlier this month it was decided that GNOME 3.8 would get rid of the GNOME Shell Fallback mode
used for running the desktop environment in a way similar to the GNOME 2 "classic" environment while also not requiring any 3D GPU/driver configuration. Earlier today there was basically a call for forking the GNOME Classic/Fallback code
so it could live on, but now it's been announced that some of the user-interface/experience elements will be brought to the GNOME 3.x world in a manner that's more easy for users to optionally enable.
Going forward it will be easier to enable the GNOME Shell to exhibit old GNOME 2.x functionality like the classic alt-tab, a task bar. minimize/maximize buttons, a main menu on a panel, etc. This isn't being done by abandoning the GNOME Shell and the GNOME3 philosophies but rather taking advantage of the extensions framework. There's already GNOME Shell extensions to provide much of this functionality, but they're not packaged in an easy-to-use manner and widely advertised to users.
The new plan is for GNOME to package up these common extensions for providing a GNOME2-like experience and treating them as a GNOME module that will be tested against new releases too. From there it will be easy for end-users to enable a configuration option or similar setting for bringing back these old GNOME 2.x traits that are desired by a measurable portion of the Linux desktop user-base.
The GNOME developers also aren't doing anything to make GNOME Shell more twekable since their view is that "there should be a single, well-defined UX for GNOME 3, and extensions provide a great mechanism to allow tweaks without giving up on this vision." The GNOME developers also have no plans to endorse the Cinnamon
More information on this GNOME "classic" experience comeback are outlined in this mailing list post
from today. While waiting for more GNOME 3.8 code to emerge, be sure to participate in the 2012 GNOME User Survey