I guess it depends on the scotch and the beer. I wouldn't go dumping my good single malt in a beer willy nilly. It might be interesting to put some Islay malt in a Porter or Stout for a nice smokey/peaty effect though. I hear of a lot of people adding Makers Mark to their Bourbon Barrel beers, so use that price point to judge where to use Scotch.
What I like about Scotch (especially Single Malt) is that its essentially distilled beer minus hops. I think, used correctly, it could really strengthen and brighten flavors in beer.
That said, I've never done it, so I don't have any specific advice to give.