Hello Tom and the rest fo the WPMUdev team.
Couple of things:
1. We added the ability to 'delete' an order to a 2.5.2 'remixed version' of your plugin here: http://plugins.twinpictures.de/fixed-plugins/marketpress/
2. While we where testing, we found an AMAZING amount of undeclared variables that throw warnings and notices when wp_debug is turned on. While this is not a deal breaker, we are a bit OCD and have started fixing them by adding checks to first see if the var isset or !empty(). Before we go too much further, is there an update to this plugin planned soon? More to the point, is there a smarter way we can work together on improving the MarketPress Lite plugin such as github.com? We would much rather combined efforts rather than deal with work-arounds/version forking/plugin remixing.
Feedback is appreciated!