I'm not familiar enough with Teamspeak to comment, but there's nothing inherently Electron-specific about this. Other clients need to grow support for Spaces, of course.
Well, in teamspeak the basic unit of organisation is a channel, and channels can have subchannels. every channel can be give individual rights which it inherits to its children. basically, exactly what they seem to have introduced with spaces. as someone who still uses teamspeak i found the "we don't have a hierarchy and every channel next to the others" quite odd. good to hear that the rest of the market is now copying this feature though, it's really useful. maybe at some point they'll get temporary channels too.