Past practice may give hints as to the release date: In 2009, Apple delivered a gold master of Snow Leopard on Aug. 12, a little over two weeks before the Aug. 28 on-sale date. On the other hand, Lion may move faster from GM to release because of its download-only distribution channel, which doesn't require time for physical duplication or shipping.

If the company follows its Snow Leopard practices, it will announce Lion's availability date several days before the upgrade hits the Mac App Store.

Apple will . For that price, consumers can upgrade Snow Leopard to Lion on all their personally-owned Mac systems.

The operating system will weigh in at about 4GB, a size that prevents users with dial-up connections from grabbing it, and makes it difficult for those whose Internet providers meter their bandwidth. Apple has said customers can and use the free Wi-Fi network there to download Lion.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at or subscribe to . His e-mail address is .