We had a brief discussion this afternoon on IRC. The log is uploaded as an attachment. The gist of it was to toss around ideas for default catalog implementations that wouldn't be a part of core but would be available as starting points for shops as part of a DC distribution.

The absolute minimum could simple be a listing of product nodes in a View at /catalog, while the next step up would make assumptions about the categorization of products to present a taxonomy based catalog at /catalog. Targeting larger sites, the basic idea is to pursue some sort of generic faceting system.

One thing this discussion really highlighted was the problem we'll have of sorting display nodes based on data contained on referenced products. This issue isn't going to go away and will need a satisfactory set of basic guidelines / best practices. I lean toward putting as much as possible on the product itself (i.e. any fields you might want to facet on) and have some sort of reverse reference so the display node can be found from the product itself. But I really don't know how that could happen. ; )