Windows 8.1 is the free and awesome update to Windows 8.0 and will be available in just a few months. Your 8.0 applications need some special TLC. Need some help finding resources? Here:
8.1 Product Guide for Developers
Developer portal article with high level descriptions of the new 8.1 features and links to more details
8.1 New APIs and features for developers
A breakdown by category of the new APIs for 8.1
8.1 Migration Guide whitepaper
Word doc on how to re-target your 8 apps for 8.1 and some of the “quirks” that you might find
Migration section of the Developer Portal
Upgrading Windows 8 apps to 8.1
Build video that covers migration to 8.1 and shows some examples
New Search Experience
Build video on how the new Search features work
Beautiful Apps on Any Size Screen
Build video how the new app size features work (versus Snap state)
The Fast Lane for App Certification
Build video on how the submission process works for 8.1
Addressing UX Design
(please add your own links in comments)!