Google's warning that the OTA Gingerbread update for the Nexus S and Nexus One might "take a few weeks" to reach all owners was a dash of unpleasantly cold water to the face; happily, xda-developers have dropped by with a hot towel. They've dug up the official links from Google for the Android 2.3.3 update, which means the impatient can now update their handsets without waiting for Google's schedule to notch along.
Two different downloads are available, one for the Nexus One:
... and another for the Nexus S:
If the links are too slow for you, there's information on mirrors at the original forum post.
[Thanks to everyone who sent this in!]