Update has been released as expected. See the latest post here and this guide to install update on rooted Nook Color.
One B&N employee has leaked on the forums that they are going to be trained for the new appstore for Nook Color on the coming Monday [ April 25] as they are not usually given too much heads up, so it is expected that the much awaited update might land on the same day.
The update is expected to bring Android 2.2 on the e-reader along with several Apps as well as an appstore type client to download more apps.
B&N had already started taking submission for the apps days before for the upcoming update. Nook Color has been one really popular e-Book reader due to its hack-ability and turning it into a full blown tablet.
Check out the sneak peak of update here.
Lets us know in comments on what are you expecting from this upcoming tablet.