After months of rumors, Google has made its entry into the cloud music space official, testing an online storage system called Google Music.The search giant unveiled the service Tuesday at its input/output developer conference, putting Apple and Amazon squarely in its sights. The online storage system, which is in an invitation-only beta phase, will allow users to store up to 20,000 songs. Once uploaded, that music can be accessed from any PC or Android tablet or smartphone. Though Google announced the service would initially be free, it hinted that it might charge users after Google Music emerges from the test period. That’s a slightly different model than the one Amazon announced in March (Variety, March 29). Users of the retail giant’s Cloud Drive receive 5 GB of storage space for free — and receive a free upgrade to a 20 GB package when they purchase an MP3 album from the site. (For people with larger collections, the company is offering a range of tiered storage plans costing anywhere from $20 to $1,000 per year.) Google, perhaps in an effort to avoid some of the backlash Amazon felt when it announced its service, has vowed it will delete user MP3s if the copyright holder has a “legitimate claim” against their music being on the server. (The company uses watermarks that some labels insert into legitimately distributed MP3 files to determine authenticity.) The lack of label support could work against Google, but isn’t expected to be fatal. Amazon faced criticism after the launch of Cloud Drive, but has reportedly been on a peacekeeping mission with music execs in New York and Seattle, seeking to strike a deal. Jamie Rosenberg, direct of digital content for Android, said at the I/O conference that Google had hoped to work with labels to sell music through the service, but the labels had asked for certain conditions that Google couldn’t accept. With Google’s entry into the space now official, all eyes turn to Apple. The company has reportedly been working on its own cloud storage system, with an enormous data farm in North Carolina expected to be the hub of those operations. Google is, in some ways, at a disadvantage in this fight. While its data storage center is certainly vast, it lacks any sort of retail arm to sell music. (The company did, however, announce a movie rental service for the Android marketplace.) Google Music users, however, will be able to import their iTunes libraries, the company said.