I saw a new copy of the 1 disc Abyss at the store today. It was in an "Awards' slipcover. The back claims it is 16.9 enhanced. Is this correct or a typo?

Typo, unfortunately. All current editions are non-anamorphic (at least in R1), and IIRC all of them incorrectly state that they're 16x9 enhanced on the back cover.

It's annoying that they can repackage and rerelease The Abyss as many times as they have, and still not make it anamorphic.

Or at least still not correct the error on the packaging. Stupid.

Or that, but I'd prefer they correct the error with the DVD.

The statement about 16:9 enhancement on the packaging refers to the menus, which are anamorphic.

Totally misleading, and yes they definitely should change it (or preferably remaster the movie).