In Brazil, we have a few. But, in general, they're not an original beer, really created by some musician, but more a marketing thing. They only contract a micro brewery to develop a recipe for then, or even use a previously existent beer and re-brand it with their names.
Examples are: Raimundos, Sepultura (which is a brazilian hardcore band well-known around the world) and Paralamas do Sucesso, bands which have a beer with their names produced by Bamberg Brewery, a microbrewery of São Paulo state dedicated exclusively to german styles. The former 2 being merely a re-brand of Bamberg's flagship beers.
Velhas Virgens is a rock band from São Paulo which have their own brand too, and more than one beer, and I think someone inside the band homebrew. Nowadays they produce in association with Invicta brewery, and I guess they have some contribution for them in the products development, although, of all those "rock band beers", they seem to be the most genuine/authentic initiative.
The way I see this thing on the craft beer scene is: people trying to take advantage of this trending market and make money out of it. It's a pure marketing thing. It's like you being a famous person and associating your name with some product, whatever it is, just because you know people will buy it only because of your image/name, and not because of what is really inside of it.
Particularly, I think this is pure opportunism.