Odd, still no update. So I downloaded it
https://www.microsoft.com/en-us/download/confirmation.aspx?id=51025
Expanded it:
expand -F:* Windows8.1-KB3132080-x64.msu d:\temp
Extracted the cab file
expand -F:* Windows8.1-KB3132080-x64.cab d:\temp
Look at the files. The update.cat was signed on January 10. Here are the updated dlls. There are tupes because some are 32bit and some are 64bit, but the list gives us some hint of what is new (Jan 10) and what is just included for compatibility (some of which i have newer on my pc already). Updating all sorts of core crypto, SMB, and Kerberos in an optional patch is ... odd. My guess is this is changes for SHA-2 authenticode enhancements that will become mandatory in future months.
01/10/2016 12:43 PM 445,440 certcli.dll
01/10/2016 11:56 AM 186,880 dpapisrv.dll
01/10/2016 12:09 PM 1,442,304 lsasrv.dll
10/28/2014 09:50 PM 736,768 adtschema.dll
10/28/2014 09:51 PM 154,112 msaudite.dll
08/22/2013 06:46 AM 61,952 msobjs.dll
10/28/2014 08:43 PM 293,376 ocspisapi.dll
01/10/2016 12:02 PM 987,648 kerberos.dll
01/10/2016 02:37 PM 442,720 msv1_0.dll
01/10/2016 11:43 AM 801,792 kerberos.dll
01/10/2016 01:39 PM 332,640 msv1_0.dll
01/10/2016 12:09 PM 324,096 certcli.dll
10/28/2014 09:06 PM 736,768 adtschema.dll
10/28/2014 09:06 PM 154,112 msaudite.dll
08/21/2013 11:17 PM 61,952 msobjs.dll
10/11/2015 01:36 AM 561,952 cng.sys
10/11/2015 01:36 AM 177,496 ksecpkg.sys
06/26/2015 10:12 PM 284,672 mrxsmb10.sys
01/10/2016 01:15 PM 202,240 mrxsmb20.sys
01/10/2016 01:15 PM 401,920 mrxsmb.sys
10/28/2014 09:19 PM 219,136 ocspsvc.exe