Online version v1.0 (only supports static meshes): http://matt3d.webege.com/
Unreal Forum topic
v1.0 Currently it only supports static meshes, porting over their location/rotation/scale, any other kind of actor or special properties are ignored. If there is enough interest the tool can be expanded to include other actors like Lights, BSP, etc.
1. You sill need to export all individual meshes & textures from UDK, and import/set them up inside of Unreal 4.
(with a lot of work, it would be possible to write a tool to convert materials exported as T3D made in UDK, into unreal 4)
2. Once they are in the Content Browser, you can copy the actors inside of UDK, use the tool to convert the output, then paste into Unreal 4.
There is still a lot of manual labor involved while re-importing assets into Unreal 4, but this tool is the first step in reducing the work it takes porting from UDK to UE4