Maybe one of your bloggers can clean this up and adapt this to a blog post for WPMU.org...
Recently, there has been a big push on the theme marketplaces to build themes with built-in support for various e-commerce plugins. Unfortunately, MarketPress is not one of those that ever seems to get supported. It's too bad though that many of these themes are really beautiful.
That's not the end of the world though. It is totally possible to built a beautiful Marketpress site using portfolio or slider themes that really showcase your product imagery.
The secret to it is the Redirection plugin
A few months ago, I built a small demo store http://demostore.teatra.de using redirection from the front page slider to the product page themselves. The redirection gives the browser (and most importantly Google) a 301 permanent redirect so it tracks it nicely.
I later then built a store for a client using the same methods http://au.the-devotea.com
In many cases portfolio themes are some of the most beautifully designed themes available. If you spend time taking great product photos, why not use the well-designed galleries and portfolio setups to showcase your products? All it takes is a little bit of creative navigation and little bit of magical redirection.
First, you setup your product page, with all your extra images, text and stuff. Then you add a separate portfolio item. In the cases of the sites I built above, they are blog posts with an excerpt designed to show up in the featured slider. The slider links to the blog post itself (which the public will never see), but the redirection is handled cleanly and the visitor is seamlessly sent to the product page. The same method would work for the portfolio items, just setup the redirections to the related product page and the customers will never see the individual portfolio item, instead being sent to the product page.
A method like this really adds a ton of visual flexibility when you are using Marketpress and opens up a massive number of fantastically designed WordPress to you. It take a little more work and manipulation to set it up, but it is certainly worth the effort and would allow you to design some really beautiful stores that goes far beyond the basic product listing layouts that come included with MP.
I just thought I'd share this because it is a method I've found to be incredibly useful