Hi liminal! Not yet, but we were just talking about it the other day -- everyone in the Looking Glass team wants to see it happen.
So, we're setting a bounty on this. If anyone in Cubeland gets a working version of Alexa controlled L3D Cube and posts a video link here before April 1, that will win a 6x6x6 L3D Cube. If more than one person post an Alexa + L3D Cube project before then, we'll have to take a little straw poll to determine the winner.
Some starting points that I found in a quick Google:
-Shawn, Looking Glass