The preview was released with the Evangelion 1.0 movie DVD. (Here's my review of the first movie.)
UPDATE: Looks like the movie below was removed by the Youtube fun police. No worries though, as it's still available via the mavericks at CrunchyRoll.com.
UPDATE 2: I will not be denied! Crunchy Roll seems to have taken the fall, but now we go all the way out to Portugal to satisfy our need for Evangelion 2.0 goodness. And with subtitles no less. Enjoy. (Source: Sapo Videos)
Now it's interesting to do a sided-by-side comparison with that fan-produced remake: