I don't know how anyone who has seen the movie (whether they like it or loathe it) can classify it as a "Musical/Comedy". If La Vie en Rose classifies itself as a musical (there ain't no comedy in this flick, let me tell you!) then basically any movie with a soundtrack can classify itself as one. The movie that people routinely come back to in defending this decision is Ray, for which Jamie Foxx won a best actor in a musical/comedy Globe. You see, the performance sequences in Ray were actually "musical sequences". They had the energy that you would find in a regular song-and-dance musical and the movie revolved around the music. Even though Foxx was miming do Ray Charles' music he was "performing" and the film felt like a movie about music rather than a movie with music in it, which is the case with La Vie en Rose. And I don't even like Ray so I certainly am not defending that movie.
No, because Edith Piaf, as played by Marion Cotillard with an assortment of wigs and Amelie impersonations, in her performances merely stands on a stage. The only time the movie becomes about the music and not about OMGMARIONCOTILLARDISEDITHPIAF!! is during the film's climactic rendition of "Non, Je Ne Regrette Rien". The music sequences are good in that the music is good, but the movie is more interested in watching Marion Cotillard act twee/drunk/depressed instead of being a film about Piaf's music, which is where the film stops being a "musical" and becomes a "drama", which is the category La Vie en Rose should have been placed.
Then again, the HFPA are weird like that. Remember when Dancer in the Dark was classified as a drama when it is clearly much more of a musical than La Vie en Rose, Ray and Walk the Line are combined? Bjork got a nomination for Best Performance by an Actress in a Drama despite a large part of the power of her performance being her musical passion.
Still, perhaps this decision will have a silver lining. Now that Cotillard isn't in drama contention she has a higher chance of losing because this year's musical/comedy category is stacked to the rafters and if something like Sweeney Todd sweeps (and some people think it deserves to) then will Helena Bonham Carter not get swept up? And you can't deny that people like Amy Adams (Enchanted) and Laura Linney (The Savages) will be very strong candidates as well.
It also means that in the drama category, where Cotillard would most certainly have won even though it's a foreign language performance, Julie Christie could have a free walk to the podium for her excellent performance in Sarah Polley's Away From Her, which I don't think anyone would begrudge. Or Keira Knightley could even give her campaign a big boost if Atonement really does explode onto the awards scene.
So, basically, it's utterly absurd and kind of insulting that they deemed La Vie en Rose as a "musical" or "comedy" (the decision is quite comedic in itself actually), but perhaps, just maybe, the "omgsheISedithpiaf" campaign will run off the rails because of it. I certainly hope so.