Noticed this on the US Open website. It's US only, but that's not a impassable barrier.
USTA to offer free live streaming on USOpen.org
More than 150 matches comprising more than 300 hours of live tennis action will be streamed for free throughout the United States on USOpen.org, the official website of the US Open.
The USTA world feed, which is fed to international broadcasters in more than 180 countries, will be streamed live during all the live television windows for ESPN2 and Tennis Channel. All five television courts with announcer commentary will be available to users in high definition.