When a camera is selected in the scene hierarchy a camera preview window shows you exactly what the camera is seeing.
This is great!
Now that is useful!
thats a cool feature 
cant wait to use it!
Wow, it is interesting how little things help so much… and make the wait for Unity3 worse.
Noticed that also, one thing I’m wondering if there’s a way to pin that to the screen when selecting and manipulating a different object.
You can pin it by locking the Inspector.
I had never even noticed the lock icon on the inspector until now.
Mind blown.
I have a really hard time going back to Unity 2.6 for other projects. The scene view is just so improved with such nice little touches. Way to go UT developers. =)
This looks useful!
Found that by accident, as it’s such a small window, but it absolutely rocks, incredibly useful especially for fine positioning.
Definitely great for positioning.
For this puzzle all I had to do was create the camera facing the right direction and line it up using the preview window.
Much, much easier.
http://hometime.net/slider_puzzle_movie/slider_puzzle_movie.html
(you won’t see how it’s used until the end of the movie)
yeah this is cool!
I also like the fact when you gonna drop a material on a object, it show you a preview if you are on the object with the cursor!
Lot of new amazing stuff in the last version ^_^!!
The one thing I must ask for every feature:
Is this Pro-only?
I seriously doubt that any editor features like vertex snapping, camera preview, etc. are Pro only.
Remember that Pro features tend to focus on rendering capabilities, flexibility (like C++ plugins), and optimization (Asset Bundles, Profiler)
Hi, btw! 
No.
Its a very cool feature though. Wish I it was draggable though.
“Wish I it was draggable”
That’s always been my first inclination, to drag it to some other place.
Is it possible along similar lines to create a camera preview just like that but one that fills the scene window or a custom EditorWindow window? And is it possible to get mouse/keyboard events within that view?
+1
I wonder, can you lock objects for preview but select others? ie lock some colliders to see their gizmos then toodle off and manipulate something else? if so I have been missing this all this time :S