CBS (NYSE: CBS) is bringing all its online music units together under one roof, the company said. The new unit, the CBS Interactive Music Group, will house CBS Radio’s roughly 100 music websites and online audio streams, as well as its various mobile apps. The creation of the interactive music group is meant to further formalise CBS Radio’s relationship to music recommender Last.fm, which CBS Corp. bought for $280 million in May 2007.

SEE ALSO: Last.fm Puts Pay Wall Around Streams In Some Markets

The two sides had been heading in that direction for a while, taking steps here and there. For example, CBS Radio began adding its streams to Last.fm precisely a year ago. By establishing a single entity around both offerings, the company should be able to get more focused results from the acquisition. For one thing, it has an attractive number of advertisers and other marketing partners: CBS says that at launch, the interactive music group has a reach of practically 40 million monthly uniques worldwide. As it moves ahead, the group will try to build on the kinds of deals that CBS Radio has struck in the past with AOL (NYSE: TWX) Radio and YahooLaunchcast. More after the jump.