I would like create web app like shopify.com. User can pickup subdomain(or domain), theme and have own store.
How can I do this? Create main application, deploy it automatically like new standalone version and update it via git?
I'm using Rails 3. Thanks for your advice.
Based on replies: When I choose to use only one application (without multiple instances) and give user his subdomain, it will looks like their own website. But everything will be in one database (It's good idea?). And how can I have multiple themes in Rails app?