Note there have been a number of unannounced build recently. they were kept quite so as not to detract from the competition announcements.
You can probably find some details in the secret beta thread.
this build was really just a quick fix for the 1st issue below as that could be a deal breaker.
-Change to the way culling is done to avoid things falling through platforms when they go offscreen etc.
-Fix so you can re-drop and pickup jetpack