I received a response from the Odoo team: "A new feature to create aliases for every URL is on its way, should be merged in master soon. It's actually a great feature, it allows to change the name of the product or title of the blog and Odoo is able to do the 301 redirect automatically because it detects the right one with this number. It's also an easy way to shorten URLs, like this: http://odoo.com/blog/5/post/156"