Hi Alessio,
I deployed ecommerce, along with a bunch of other packages, in July of this year with OACS 5.1.5. I've got the 5.1.5 (actually 5.05, I think) version running on my devel server with 5.2.0, and after a couple of small deprecated function fixes, it works OK. Torben and I each have a bug open about these deprecated functions...but Torben's deprecated functions don't seem to be causing my instance any pain. But then, it is not yet in production use.
I'll take this opportunity to let you know something that I didn't know coming in: ecommerce is not a complete app, as installed from the package repository. It's more of a kit. And some of the pieces don't actually work. But, I (a complete tcl, aolserver, and oacs newbie) was able to get a pretty full-featured store (plus all of the other apps and web design--but ecommerce took the majority of the time) up and running in about three months of evenings and weekends, so it's not all that tough to do. 😉
In short, I suspect you can grab the ecommerce code from CVS and install it into your OACS without two much pain. I have not touched the CVS version--I hadn't yet figured out the development/release process of OACS when I was building my store--but I suspect it is probably no farther from working than the 5.05 release.
