We usually don't cover update particulars, but this one is very interesting. Change logs always claim better battery life, and most of the time the end user does not notice a difference. That is about to change. If you find yourself scratching your head and wondering what CDRX is, do not fret, we didn't neither. Connected Discontinuous Reception, or CDRX is Motorola/TI's codename Wrigley 4G LTE baseband. CDRX will equate to better battery life and will be included in the 6.12.173.XT912.Verizon.en.US update that is rolling out to Motorola Droid RAZR/Maxx users at this time. Motorola has really stepped up their game in regards to battery life in regards to Smart Actions, the MAXX's massive battery and now CDRX.

For a detailed explanation of CDRX and how it will effect battery life, ANandtech wrote a fantastic article below.

Discontinuous Reception (DRX) is nothing new for UMTS based networks, and is a power reduction feature. The aim is simple - during idle periods, the cellular network tells the handset that it doesn't need to expect any traffic, and thus the handset can shut down the RF frontend and other power draining bits. The phone can then wake up the parts required to receive and listen to a paging channel when the discontinuous cycle ends.

The above is the way things work in UMTS, in 4G LTE things change a bit, but the concept is the same. However a new feature is the somewhat strangely-named connected DRX mode. The "connected" part comes from the fact that DRX now can work while the user equipment is in an RRC_Connected state, in addition to RRC_Idle. The result is that the handset can now shut down parts required to listen with much finer frequency, for example during the idle periods when a webpage is loading, as opposed to the longer idle periods when the phone is locked and in a pocket.
Source: Anandtech