Google has released a small update for the Nexus 7 (2013) LTE, iterating its version number to Android 4.3.1. This is the first actual step up for the newly-released tablet, and the first device to go above Android 4.3 in general. While the changelog does not give any details, the new build number JLS36I is only a slight bump from the shipping version of JLS36C.
As we near the impending release of Android 4.4
Key Lime Pie KitKat, we can make a large and likely correct assumption that any remaining updates to Jelly Bean, such as this one, will be maintenance bug fixes. No word on whether the other Nexus devices will receive the same bump to Android 4.3.1.