Brandon LeBlanc over at the Windows Blog has announced that February 10th will be the cut off day for Windows 7 BETA downloads.
The shutdown of general availability for the Windows 7 Beta will occur in 3 phases over the course of the next few weeks:
Starting January 27th, the Windows 7 page will be updated with a warning that time is running out on downloading the Windows 7 Beta and that we will be limiting downloads shortly. People will be encouraged to register and start the download of the Windows 7 Beta sooner rather than later.
February 10th, new downloads of the Windows 7 Beta will no longer be available. People who have already started their Windows 7 Beta download and have not yet finished will still be able to finish their download and are encouraged to do so.
February 12th, people will no longer be able to complete their download of the Windows 7 Beta. Anyone who hasn't finished downloading the Windows 7 Beta will be unable to do so.
Product keys for the Windows 7 Beta will continue to be available. So if you have the Windows 7 Beta but didn't get a product key you will be able to do so even after February 12th.
If you have not already downloaded it, you still have some time, but make sure you get it before that day.