Live Search's Weblog has a post that gives an insight on "gears and inner workings hat we expose in our advanced
syntax." The operators enable you to do some interesting things with macros. Using the new operator: LinkFromDomain, your search would include all sites that are linked from a given domain. Here are the results for Unoffical SEO Blog.
Macros allow you to bundle up syntax into easy to reference keywords. Using the advanced path in the macro creation wizard, you can experiment with different syntaxs and preview the results versus the normal live search results.
You can "learn and play at the Gallery": "While we’ve got some plans to get macros in the hands of every user, in the meantime, you can try out, see how macros work, and share your own macros at Gallery.Live.com. In addition to lots of user crafted macros, the search team has seeded the gallery categories celebrities, sports, and cities in culture."
The improvements will empower users to use the link structure of the web.