Dota 2 has been updated to support the Xbox 360 controller when you're spectating, Valve has announced.
When in Dota 2 TV the Xbox Controller can be used as follows:
Left / right bumper = Cycle back or forward through the heroes on the field
Start button = Pause (Replay only)
Back button = Rewind (Replay only)
D-Pad up / down = Cycle through stats dropdown menu
D-Pad left / right = Slow down or speed up replay speed
Y button = Show gold graph
X button = Show XP graph
B button = Dismiss open graphs, reset playback speed, revert camera to previous mode (after cycling heroes)
The update also offers a host of user interface, matchmaking, audio and gameplay tweaks and fixes.