As written in the email to LEGO® Universe subscribers:

Hello Adventurer, today we are very sad to announce that LEGO® Universe will be closing on January 31, 2012. This was a very difficult decision to make, but unfortunately LEGO Universe has not been able to attract the number of members needed to keep the game open.

We realize how sad this will make the many players who have enjoyed LEGO Universe and we are committed to providing open communication with both kids and parents as we transition through this difficult time. We understand this is a challenging change and apologize for not being able to give parents forewarning before the general announcement.

We are thankful to have had the opportunity to share this adventure with an amazing community of players. We hope you will continue to enjoy LEGO Universe for the last few months. As a thank you, if you are a paying subscriber on December 31, 2011, we will provide you the full game for the final month for free.

Again, we want to thank the fantastic community of players who made LEGO Universe such a vibrant, fun and creative experience.
Sincerely,

The LEGO Universe Team

The Details:
The game will be turned off on January 31, 2012 at midnight (EST).
All current subscribers (1, 6 or 12 month plans) who still have active subscriptions on December 31 will receive a refund for any remaining game time remaining after December 31 as well as free play from January 1, 2012 until January 31.
For example, if you purchased a 6-month subscription on September 1, 2011 (which would expire on February 29, 2012), you would be refunded $16.66 for the 2 months following December 31.
We will begin processing all refunds on February 1, 2012. All refunds will be made to the credit card used for the original subscription.
If your subscription expires before December 31 you will need to purchase an additional 1 month subscription by December 31 in order to get the free game play in January (again, any unused game time as of December 31 will be refunded.)
LEGO Universe game cards can only be used until December 1st 2011. Unused game cards after December 1st can be converted to LEGO Shop @Home gift cards for the same value.
Please note: Details on how to convert unused game cards will be posted on December 1.
You can continue to enjoy the free to play zone until January 31, 2012 but your last chance to convert to a paying subscription is December 31, 2011.
Click here to read more.