Over on Windows 7 Team Blog, Brandon has a post explaining that we are coming to the end of the availability period for the beta.

Originally we said it would be available until at least this weekend, but downloads are going to continue into February – in case of a last minute rush we’re making sure that anyone who starts a download which fails, will be able to resume it for 48 hours after the cut off. If you’re a technet or MSDN subscriber, in which case it will still be on the download site; if not and you haven’t got a copy you have until Feb 10th to start your download.

For now I’m assuming the same applies to the server products.