From the Springboard Series Blog:
Because interest in the beta is so high, we have decided to extend availability of the beta through the Customer Preview Program (CPP) until 2/12.
Note that MSDN and TechNet subscribers will continue to have access to the beta after the public program closes.
Also, even after we shut off downloads from the CPP, you will still be able to register and get a key; just not be able to download the product.
No new downloads (2/10)
You will no longer be able to initiate new downloads of the beta in this phase, but you will be able to complete a download that you had previously initiated. You will still be able to obtain product keys to use with a DVD or bits you have previously downloaded.
No downloads (2/12)
The beta will no longer be available for download, but you can still obtain product keys to use with a DVD or bits you have previously downloaded.
If for some reason, you still haven’t gotten hold of the Windows 7 beta, I suggest you head over to the Windows 7 Beta Download website ASAP and grab a copy! You’ll love it!