I feel that the stronger versions of American "IPA" are more accurately described as Imperial Pale Ales. Pale in color with a malty backbone, but very hop forward, and a strong alcohol presence. I think we will soon be branching out with our use of IPA or Pale Ale, such as Citrus Pale Ale, Summer Pale Ale, Winter Pale Ale, etc. I already found Elysian Brewery experimenting with citrus flavors in a Pale Ale (Elysian Superfuzz Blood Orange), which was pretty tasty for the summer.
Personally, I brew a lot of American IPA's using American hops; again very hop forward beers with strong hop presence in the flavor an aroma, but I also experiment with old time British (Burton Upon-Trent) styles, where I try to use European and British hops to recreate the what the original IPA's may have been like...always incorporating some light oak to give it a more genuine taste.
As mentioned before in other posts...read Mitch Steele's book "IPA: Brewing Techniques, Recipes and the Evolution of India Pale Ale" and use the recipes within to get a better understanding of the differences between the IPA styles and ingredients used.