A newly announced Pentax K-3 DSLR features "the world’s first AA filter simulator, which reproduces the effects created by an optical AA filter. By applying microscopic vibrations to the CMOS sensor during exposure, the K-3 minimizes false color and moiré. You have a choice of three settings to obtain the desired effect: “TYPE 1” to attain the optimum balance between image resolution and moiré; “TYPE 2” to prioritize moiré compensation; and “OFF” to prioritize image resolution. Thanks to this innovative feature, the K-3 offers the benefits of two completely different cameras — the high-resolution images assured by an AA-filter-free model, and minimized false color and moiré assured by an AA-filter-equipped one. You can switch the AA filter effect on and off as you wish."
A Youtube video shows how it works: