I went through the literature on background music in September 2012; here is a dump of 38 paper references. Abstracts can be found by searching here and I can provide full texts on request.

Six papers that I starred in my reference manager (with links to full texts):

• Chamorro-Premuzic, Tomas, Montserrat Gomà-i-Freixanet, Adrian Furnham, and Anna Muro. 2009. “Personality, Self-Estimated Intelligence, and Uses of Music: A Spanish Replication and Extension Using Structural Equation Modeling.” Psychology of Aesthetics, Creativity, and the Arts 3 (3): 149–155. doi:10.1037/a0015342.
• Dobbs, Stacey, Adrian Furnham, and Alastair McClelland. 2011. “The Effect of Background Music and Noise on the Cognitive Test Performance of Introverts and Extraverts.” Applied Cognitive Psychology 25 (2) (March 23): 307–313. doi:10.1002/acp.1692.
• Hallam, Susan. 2012. “The Effects of Background Music on Health and Wellbeing.” In Music, Health, and Wellbeing, edited by Raymond A. R. MacDonald, Gunter Kreutz, and Laura Mitchell. Oxford, UK: Oxford University Press. doi:10.1093/acprof:oso/9780199586974.003.0032.
• Perham, Nick, and Joanne Vizard. 2011. “Can Preference for Background Music Mediate the Irrelevant Sound Effect?” Applied Cognitive Psychology 25 (4) (July 20): 625–631. doi:10.1002/acp.1731.
• Schellenberg, E. Glenn. 2012. “Cognitive Performance after Listening to Music: A Review of the Mozart Effect.” In Music, Health, and Wellbeing, edited by Raymond A. R. MacDonald, Gunter Kreutz, and Laura Mitchell. Oxford, UK: Oxford University Press. doi:10.1093/acprof:oso/9780199586974.003.0022.
• Waterhouse, Lynn. 2006. “Multiple Intelligences, the Mozart Effect, and Emotional Intelligence: A Critical Review.” Educational Psychologist 41 (4) (December): 207–225. doi:10.1207/s15326985ep4104_1.

One-word summary of the academic literature on the effects of listening to background music (as of September 2012): unclear