Apple Computer Inc. on Wednesday unveiled iTunes 4.5, a new version of the company's music jukebox software that contains many new features. Included in the new version is iMix, Music Videos, Video Trailers, a new lossless audio codec, free weekly downloads and Radio Charts. According to information posted on Apple's Music Store early Wednesday morning, iTunes users now have access to a free downloable single, which will be made available every Tuesday (spotted at Neowin).