From majornelson.com:

I wanted to remind everyone that this weekend is a Free Gold Weekend for European Xbox LIVE members. That means Xbox LIVE Free members will have access to features normally reserved for Gold Members….PLUS EVERYONE can help make a Guinness World record attempt through Kinect Sports this Saturday, April 23rd.

Marking a free weekend of entertainment on Xbox LIVE, dubbed Xbox Nations, Kinect Sports players around the globe will join together and attempt to break the Guinness World Record for the ‘largest online 100m sprint’ at 1pm ET on Saturday, April 23. (Find out what time in your region) Players can participate by jumping on Xbox LIVE, firing up Kinect Sports, and running a 100-meter dash event at 1pm ET. Each and every runner will be rewarded with an exclusive Xbox and Guinness World Record Avatar t-shirt