Twixtor enables you to speed up, slow down or frame rate convert your image sequences with visually stunning results. In order to achieve its unparalleled image quality, Twixtor synthesizes unique new frames by warping and interpolating frames of the original sequence... employing RE:Vision's proprietary tracking technology that calculates motion for each individual pixel.
The "Download" link provides the FxPlug for Final Cut Pro 7 and X, but it's available for other NLE's and MoGraph packages on this page.