They're always in the readme file in the SDK itself (along with the past ones.)
Here's 2.1.4:
Release Notes
v2.1.4
General Changes:
Update minimum firmware versions for certain products Fix some minor documentation errors in the programmer’s guide. Fix a memory leak caused by the Picker class Fix a bug where some apps incorrectly report available updates via Garmin Express Simulator Changes
Update battery status settings dialog to allow floating point input Add a menu option that allows the user to select where to save the last recorded fit session via a save file dialog. Fix a bug where menu bars were not visible when native menu views were active on touch-screen edge devices. Fix a simulator crash when launching apps in certain cases Fix a bug where incorrect error messages were reported when exceptions are not caught Known Issues:
If an Exception is thrown from a catch block, the finally block of the current try/catch/finally will not be executed.
Changes like that require updates to the virtual machine, which is part of the device firmware. Those updates will trickle out and are not really under the control of the ConnectIQ team.
