Originally we planned to release the 0.45, currently on experimental branch, to stable today. However feedback from experimental identified a flaw in a newly designed system to handle player movement. This causes the server to, when faced with complex geometry, come up with a different acceptable pathing result than a client. When the server and client have differing states, the server "wins". Therefore the place your client lets you go gets "reset" and you warp back to your position.
This is very frustrating as I am sure those testing on experimental will know. We know exactly the problem that causes this, it's not a bug in a traditional sense but a problem with the approach we used. Currently that approach is being rewritten.
What we did do was merge in some changes to 0.44 that enhance security. There are some loopholes in the game that have not been utilizing our client-server architecture and we will continue to work on these to reduce the impact of hacking and exploiting in the game.