Just in time for tomorrow's Google Music announcement, iTunes flipped the switch yesterday on its much ballyhooed (and a little delayed) matching service. To recap: for $25 a year, iTunes Match will store up to 25,000 songs from your collection on their servers for you. If you have mislabeled songs or songs with no information about them (like those downloaded illegally from torrent sites), the service will give you legal versions. Once the songs are on the servers, you can download them to other devices and computers of your choosing.