Unity version 4.2 is available now and there are some important stuff that you can read here about this new version: http://blogs.unity3d.com/2013/07/22/unity-4-2-has-arrived/

More free tech

We’ve decided to make a number of existing Unity Pro features available to users of the free version of Unity:

• Realtime shadows (one-directional light only; hard shadows only).

• Text-based serialization of materials, prefabs, scenes etc. for easier version control.

• NavMesh baking (OffMeshLinks still require Pro).

Now, games created using the free version of Unity can benefit from realtime shadows and game actors navigating intelligently. In addition, as a developer using the free version of Unity you can cooperate with your colleagues using any version control system, because text-based serialization no longer requires a Unity Pro license