I was playing around on WebSiteTest today – trying out it new IE9 test feature, and I noticed something new that IE9 does: preconnect.

What is preconnect?  Preconnect is making a connection to a site before you have a request to use that connection for.  The browser may have an inkling that it will need the connection, but if you don’t have a request in hand yet, it is a speculative request, and therefore a preconnect.

via Mike’s Lookout » Blog Archive » The Era of Browser Preconnect

Interesting behavior from IE9, making connections to sites in the hope that there will be additional resources that need to be downloaded. If IE9 becomes widely adopted (which seems likely) then taking this behavior into consideration when building a site may be useful.