updated 12:54 pm EST, Mon November 4, 2013
Joins previously-rumored Mail update
Apple is preparing updates to several core apps in OS X Mavericks, sources say. The people note that Apple is now seeding new versions of Safari, iBooks, and Remote Desktop to its workers, as well as a previously-rumored Mail update. The Safari code is identified as v7.0.1, and expected to provide a number of bugfixes. The same description applies to iBooks 1.0.1, and Remote Desktop 3.7.1.
The Mail update will allegedly be delivered as a separate "Mail Update for Mavericks 1.0" release, instead of as part of OS X 10.9.1, which would be standard procedure. This may be due to the fixes mentioned in its release notes, which specifically target problems with Gmail, including the use of custom Gmail settings.
When the new apps will be rolled out to the public is unknown, but Apple typically releases small-scale patches no later than a couple of weeks after they seed internally.