In game development, I'd say it's on the A-list and you'll asked "Why did you do that?" if you chose to embed Python or Ruby into your commercial game instead of Lua, especially if your company is a large enterprisy game development house.
Python & Ruby are languages widely web development, but only to the level below enterprise.
I see, thanks, this is interesting. I'm wondering why some languages become associated to specific fields (e.g. Python in scientific computing, PHP and Ruby in web development etc.), I suppose it is a combination of language characteristics and ecosystem. For reference, here's a link to a list of game engines with Lua scripting: http://gamedev.stackexchange.com/questions/56189/why-is-lua-...
