Recently, Nvidia, the manufacturer of current leading Tegra 2 dual-core 1Ghz processor for ASUS Eee Pad Transformer and other android tablets announced the upcoming of a quad-core Tegra processor with 12-core NVidia GPU that supports 3D stereo.
This is going to be very interesting as we are getting more and more powerful CPUs on Android tablets.
We will definitely NOT be seeing any quad-core equipped tablets any time soon but there may be companies implementing them quickly by end of this year.
As for iPads? They are going to have a hard time keeping up with Nvidia