A few days ago I have enabled the new Stamper website: http://stamper.metasys.pl. A lot has changed but the most importantly Stamper demo is available live. You can actually see it for yourself!
There are two interesting places you can visit. First one is the Stamper Configurator, a new, separate from Alfresco, web application where you can configure Stamper. This application is using CMIS to access the repository (because all configuration objects are stored there). I have plans to support Nuxeo soon, some preliminary work has been done and it is looking promising! The Stamper Configurator is available here. Login credentials are admin/admin.
Second place is the Alfresco repository itself. You can log in there as admin/admin (by the way the repository is reinitialized every day so no damage can be done there! :-). There are a few PDF documents there as well as two simple Stamper configurations, the first one contains cover page and page layer and the second one just the page layer. To stamp a PDF file just use the Stamp document option in a document’s context menu.
I will be also attending the Alfresco DevCon 2011 in London in November, I hope that this will be a good place to chat about Alfresco, Stamper and other interesting topics. Fell free to ask questions!