I see USA Today have an article on the latest findings on the "Mozart effect". The so-called "Mozart effect" refers to two quite different phenomena. The more common concerns short-term increases in spatial abilities that are said to occur from listening to music composed by Mozart. This particular effect, while it has received a lot of popular press, has been recognised for some time as being small, unreliable, and chiefly reflecting arousal.
The other phenomenon refers to the possibility that formal training in music yields nonmusical benefits. Notwithstanding the remarks of the article (and indeed, I would be loath to endorse a connection between music training and IQ), there does seem to be growing evidence for other benefits of musical training. My news items for July include the latest report on that effect, and you can also find links to earlier, related news items.