When a user goes to the site and request the following page: myworld.com/blog is it possible to deliver the contents from /blog/ from a different server which is the physical location for blog.myworld.com? Is it possible to mask a subdomain URL to look like it is a subfolder of a domain so Google and users see myworld.com/blog? is this good practice for SEO?
Not totally sure of why you're trying to do this? Maybe you can add more information.
If you want to pull content from another server or location, there are several ways to do it - virtual directories, RSS feeds, etc (see links below). However, if you are trying to hide the source of the content from the user, Google would probably interpret that as cloaking which is bad for SEO.