Hi Jon,
ecommerce is not compatible with version 5.2. There is a bug in the bug tracker containing a list of procs that were deprecated prior to 5.2 and removed from 5.2 which would prevent it from working. Also, there are a bunch of feature suggestions there (and many other implied feature suggestions from some who have asked in the forums for different features).
Instead of working on yet another upgrade for some very early versioned tcl, I've decided to hack it up into separate packages to better handle use cases, and use some of the newer available OpenACS features.
The new version is meant to work with 5.2 (even if 5.3 is released before its done). And I plan to have an upgrade path, since the data model will change little.
