The initial CMS implementation assumes that you will be using an edge server (e.g. Amazon/Akamaii etc.) for images. To facilitate this, requires to steps. First, you would update the asset.server.url.prefix property found in common.properties for at least the production environment. Second, when you are rendering images, use the UrlRewriteTag so that the prefix is properly prepended to your URLs.
This works for CDNs where you specify an origin server. The CDN will look up the image from BLC (which reads the blob from the DB) the first time only.
We are considering other image distribution approaches but nothing is on the immediate roadmap as we believe our current approach can be configured to handle most needs nicely. For those that don't want to use a CDN, they could use a local Apache proxy (e.g. using a squid server) as the image endpoint.