Maxis just announced on the official SimCity forums that the Cheetah speed feature, that was removed after launch to improve server stability, is being tested this weekend on the official test server, together with several new features that are scheduled to be implemented in the upcoming patch.

While I personally never felt the need for it (I like to actually micromanage my city instead of risking to miss important events while things move too fast), Cheetah speed has been one of the most requested features between virtual mayors, so I can definitely imagine its return will please quite a few people.