Is the nikon af-s ed 24-85mm f3.5-4.5 G compatible with nikon d7000?

And is it any good in low light action, like dancing or live concerts?

Yes its Compatible and No it's not good for low-light
i suggest you get the Sigma 17-50 2.8 or get Tamron 17-50
its a fantastic glass giving you a Wide-tele zoom and its good in Lowlight esp for Concerts.

Yes it is. All Nikkor AF, AF-I and AF-S lenses are compatible.

The 24-85 mm is slower that the old 24-85 mm f/2.8~4, but with the superior low light performance of the D7000, you should find it useful in low light. Set the cameras ISO to 6400 and shoot in RAW. When processing the RAW files, you can use the Luminance tool to reduce any noise.