General Are apps and widgets OS version specific?

view story

http://androidforums.com – Recently got a lovely S3 and a nice collection of apps and widgets. With the imminent release of JellyBean does it mean that some of the apps and/or widgets might not work? Im guessing the answer is yes. If so, does it mean I have to go through every app and widget one by one and see if a JB version exists on the Store? Thanks David (General)