In the US we use either 720x486 or 720x480 rectangular pixels. The first works with BetaSP and DigiBeta Tape. I've heard that the Media100 Nonlinear editing systems use 640x480 but I'm not sure. The Avid systems definately use 720x486. When I edit for DV Tape or DVD I use 720x480, once again in rectangular pixels. That still fills up a TV screen. I've worked on the titles and credits for one HD Independant film and was told by the editor to give him my shots as 1920x1080 using square pixels. I don't know how universal that is. The image I've uploaded shows the basic preset settings offered by Adobe After Effects. The D1 and DV items are rectangular pixels *unless otherwise identified.* It's a good little reference for sizes.

Before they made me they broke the mold!
http://home.roadrunner.com/~kflach/