Madda

Have you ever noticed how many bands and artists with a Rock background have been employing more and more electronic sounds and vice versa? I realized this the other day, while posting in the review of Radiohead's OK Computer, here in Music Banter.
What do you think about this mixture of two completely different genres?
In your opinion, when does an artist stop being part of the Rock scene and start being part of the electronic scene and viceversa?
Use bands and musicians as examples, if you want.
I mean, with certain bands it's easy: even if Muse use synthesizers and made one or two pseudo-dubstep songs, they're clearly rooted in Rock culture. But it's not that easy with stuff such as MGMT, Chemical Brothers, Primal Scream, Stateless, Gorillaz and so on (or even with older stuff such as David Bowie.. or with my fellow italians Trabant and My Awesome Mixtape, but I think that nobody knows them outside Italy ahah). They are really far from both Jimi Hendrix and Burial, to name respectively a "pure" Rock guitarist and a Future Garage producer and DJ.
These questions are not related to the music itself. I don't wanna start a debate on whether they suck or not. It's more about the cultural side. Do you consider bands like these part of the Rock culture or part of the electronic culture?

P.S. I have the bad feeling that I made a lot of errors or that I haven't been clear. I'm not english... so, feel free to correct me or to ask for clarifications