For those unfamiliar with ApexLib, it's a development framework that improved the out-of-the-box features of Apex. In part thanks for Patrick Wolf moving to Oracle, we now find a lot of these features incorporated into the Apex 4.x product, such as the Apex Advisor.
Message: Object doesn't support this property or method
The long and short of it is we need to use
This is documented specifically at the JQuery website, with further documentation about using jQuery with other libraries.
Here is all I needed to do - add the jQuery.noConflict line and modify the prefixes to use $j.
If you are currently running Apex 3.2 and plan to upgrade to Apex 4.x, this OTN forum entry may also be of interest.
As for the post title, it's funny the random things that make you think of something from a long time ago... I digress.