2:3 Pulldown is a Pulldown pattern designed to imitate the telecine pattern used when transferring film to video tape for NTSC broadcasts. It can be used to convert to actual NTSC framerates of 29.97fps when starting with video running at 23.976fps. If the source video runs at 24fps it will result in 30fps output. This isn't compatible with (analog) NTSC television, but can be useful for formats specifically designed with HDTV in mind. 2:3 Pulldown is often referred to as 3:2 pulldown.
Performing 2:3 Pulldown
2:3 Pulldown can be performed on MPEG-2 files by DGPulldown, a utility for applying pulldown flags in a number of different patterns. You can find more information plus a download for DGPulldown on Donald Graft's website. Although Pulldown flags are supported in AVC video, there are no consumer tools currently available for adding them.
Digital Video Fundamentals - Frames & Framerates