We've wrapped up the Beta1 version of Commerce for Umbraco. It's ready for your evaluation and/or usage. Feel free to give it a go! I paid particular attention to the installer routine since this was one of the most-often cited issues from the preview releases. While it's far from a one-click install I think you'll find that it's not difficult. To that end I recorded a 7-minute long screencast of the install process. You can get it from here (no audio, sorry):
I've also placed it on YouTube but the quality is quite poor.
You can download the latest Commerce for Umbraco release here.
The project's home page remains here.
As always, please let me know directly or create issue at the CodePlex site.
-Paul