Yes, from now on, new shoppers will be able to chose if they want to create a user account or not while placing an order - as long as they are not logged in already. Customers who already have a user account can also place orders with the same email address. The new guest order won't be added to the already existing user account.
After having sent the order, customers will receive an order confirmation email as usual - but this time, the email will include a link to an order page or their virtual user area. The link will be valid for one year and the page will include most of the functions like in the "usual" user account. It will also be possible to register as a customer with the used email address afterwards.
Customers will be able to place as many guest orders as they like with one email address. There will be shown only one order in the virtual user area though. This is why customers should really keep the email or save the link.