Update: Turns out that Google has been using this flatter logo for sometime now in printed promotional materials. I just checked a mailer, which I received from Google sometime back and it has the flatter logo. You can also find this (so called new) logo in official Goople Apps icons & logos section.
Also, The Verge claims to have learnt from a credible source that it is not the next Google logo.
Earlier: If hints present in the latest Chrome Beta APK are any indication, Google is planning to release a revamped version of its logo. First spotted by folks at 1,2).
As you can see above, the 3D look and depth is gone and also the colours have been tweaked a bit to give a logo a more modern look. There is no word on when the new logo will become official; clearly someone working on Chrome jumped the gun by including the new logo in latest version of Chrome beta.
To remind you, the last tweaked version of the Google logo was introduced back in 2010, which was also not a huge change like the upcoming version (if it becomes official).
While we wait for the search giant to announce the new logo, check out the previous Google logos below.