This update was released on January,18th,2014 and that was also available for small number of customers that have experience issues with December update..It is not mentioned in the Surface Pro 2 update history page .
Actually Microsoft worked out to fix the problem in holidays.Here is a reply from TmHogg from Microsoft:
We are working through the holidays to deliver a fix for the small number of customers that have experience decreased battery life and booting/sleeping problems as a result of the December update. We took the update down to prevent additional customers from ending up in this state. All hardware failures, none of which are known to be caused by the December update, are being handled promptly through our warranty exchange policy.
The UEFI firmware that we released in the December update prevents some devices from entering sleep mode (and other low power states) properly during periods of inactivity. In order to release an updated version of the UEFI firmware we need to test the new version with the other drivers in the set to make sure we are not releasing yet another unknown state to customer machines. We certainly feel your pain and assure you that we are doing everything possible to make this right, as quickly as we can.
Verge also confirmed this:
Microsoft is re-releasing its latest Surface Pro 2 firmware update today. Following issues with the update last month, the software maker pulled it to investigate and correct the problems. Initial reports revealed failed installations and battery issues in instances where the update was successful. Today’s firmware update appears to replace the existing version released in December, and is being offered to systems with or without the previous version.