It's not a major change to the way you play Xbox, but a change all the same. Graeme Boyd, European community manager, tweeted that 'Xbox LIVE Silver Membership' will now officially be called 'Xbox Live Free Membership'. Microsoft has kept its branding consistent, so this probably means a name change in North America and Australia as well.
This change comes as the price of Xbox Live is set to rise in November. It might also be to help the expected influx of new users when Kinect launches. It will be easier for the 'casual' gamer to differentiate the difference between membership levels.