by Stephen Thomas ErlewineThe soundtrack to David O. Russell's 2004 "existential comedy" I Heart Huckabees is by acclaimed songwriter/producer/multi-instrumentalist Jon Brion. Since the watershed year of 1999, when he produced Fiona Apple's second album, When the Pawn Hits the King, and wrote the score for Paul Thomas Anderson's third film, Magnolia (including producing Aimee Mann's songs for the film), Brion's stock has been on the rise, and he's been in high demand as a collaborator and film composer, which means that he hasn't had a chance to release a solo album since 2001 (and even that was only available through his website, www.jonbrion.com). So, the presence of five new Brion pop songs on the I Heart Huckabees soundtrack is big news, but the score would have been noteworthy without them, since it's one of his best scores to date. While there are elements of the carnival-esque sound of his Magnolia score -- after all, that is his signature -- as well as his moodier charts for Punch-Drunk Love and Eternal Sunshine of the Spotless Mind, Huckabees has a mischievous, impish spirit that distinguishes itself from those three other major works. There's an offhanded virtuosity in the arrangements and eclecticism that's rather astonishing -- the music is so whimsical and light on its feet, so entertaining in its kaleidoscopic array of colors and sounds, that it takes close listening to realize how clever and subtle it all is. That alone would have made Huckabees more than worthwhile, but those five new songs are all pretty terrific too. Anybody familiar with Brion's collaborations with Mann and Apple will not be surprised by what's here, but these songs are so well-crafted -- so sturdy in their melodicism and so imaginative in their production -- that they're impossible to resist; they're appealing on the first listen and grow more emotionally resonant with each spin. Hearing these, it's hard not to wish that Brion would record a full-length album of original pop tunes, but they're a joy to have here, paired with an equally charming score. Sure, it's possible to separate these five songs out and have an EP of Brion pop songs, but with these tunes scattered throughout the record, the album winds up with a freewheeling, appealingly messy vibe that perfectly fits Russell's film.