From Kotaku:
“We basically ran out of code, so next week we are going to go live with the whole thing publically so anyone can download it,” Wilson said. “We’ve been sneaking on to see what people think of it and people are really getting into it…”
That’s a quote from Gareth Wilson from Bizarre Creations who then goes on to say that some time next week the beta demo thing for Blur will be open to all Xbox Live gold members. Before you decide whether or not you want to take the time to download the demo you could always read my impressions of it here.