Cydia Substrate had been updated twice, once to version 0.9.5100, and again to version 0.9.5101. Both updates are mostly developer oriented with no consumer facing features that everyday users will notice.
The first update can inject into more iOS 8 daemons, find more private symbols, and more. The second update fixes an incompatibility with the first update. Check inside for the full change log.
Cydia Substrate 0.9.5101
Fixes an incompatibility introduced in 0.9.5100 with some combinations of extensions (the most common conflict was having both CC Settings and GroovyLock).
Cydia Substrate 0.9.5100
Includes features requested by developers, so their extensions may require this update: it can inject into more iOS 8 daemons, find more private symbols, move more arm64 instructions, and hook even shorter armv7 functions.
Now that most of the stability related updates are out of the way, it looks like Saurik is working closely with developers to meet their specific needs.
Theses updates are recommended for all jailbroken users. You can find them right now by simply opening Cydia and performing a refresh.
Have you updated yet? How has your experience been with your jailbroken device thus far?