Apple releasing iOS 8.4 an hour before Apple Music launches
Apple Music is Apple's new streaming music service, Internet radio station, and social platform for artists. Full access costs US$9.99 a month, although you can listen to streaming music and Beats 1 radio for free.
The service officially kicks off at 9AM pacific time tomorrow, which Apple Music senior director Ian Rogers confirmed on his own blog.
The update will also include other updates and fixes, and presumably a fix for the bug that crashes iPhones when a specific text string is sent to Messages in a chat.
Check out TMO's Apple Music FAQ for more info about the new streaming music service.