Amazon today announced a number of enhancements to its Amazon Cloud Drive and Cloud Player, including an unlimited music storage option and a Cloud Player for iPad.

For a limited time, Amazon customers who purchase a $20 annual Cloud Drive storage plan will receive unlimited storage space for their MP3 and AAC (.m4a) music files. Previously, Amazon Cloud customers automatically started with 5GB of free storage, upgradable to 20GB with the purchase of an Amazon MP3 album. Additional storage space could then be purchased in plans beginning at $20 per 20GB per year.

In comparison, Google Music Beta offers free storage for up to 20,000 songs, although it is unknown what if any subscription plans Google might offer. Meanwhile, Apple plans to launch its iTunes Match service in the fall, which will allow customers to "back up" up to 20,000 non-iTunes music files to the cloud for $24.99 a year.

While Amazon customers can also upload photos, videos, and documents to Amazon's Cloud, the unlimited storage offer applies only to music files. Amazon did not elaborate on how long the "limited time" offer would last.

In addition, storage of Amazon MP3 purchases will be free in the Cloud Drive, including all purchases made before the launch of Amazon Cloud. As before, Amazon MP3 purchases don't count again customers' Amazon Cloud Drive storage quota. Amazon said customers who qualified for 20GB of free storage from earlier promotions will receive the unlimited space for music at no additional cost.

Also new, Amazon announced it had release a Cloud Player for Web on iPad. As with Android smartphones, Android tablets, Macs, and PCs before it, the iPad owners will be able to play music files stored on Amazon's Cloud servers as well as those stored on the device. However, conspicuously absent from the announcement was any mention of the service working on other iOS devices such as iPods and iPhones.