In the course of announcing stellar third quarter results today, Apple confirms that Lion will be released tomorrow. The new OS will only be available via download from Apple's Mac App store for $29.99. It's approximately a 4 gigabyte download, and will require roughly 8 gigabytes of free space to install.
Users will need to be running Snow Leopard, OS X 10.6.8 in order to download or install Lion. Lion also requires a minimum of 2 gigs of RAM and an Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor to run.
Apple has just released via Software Update an upgrade to the Snow Leopard Migration Assistant:
This update addresses an issue with the Migration Assistant application in Mac OS X Snow Leopard that preents transfer of your personal data, settings, and compatible applications from a Mac running Mac OS X SNow Leopard to a new Mac running Mac OS X Lion.
I suggest updating your Snow Leopard Migration assistant before downloading Lion. MacinTouch has some excellent suggestions about udates, and even more importantly, how to backup before installing Lion.
Classic apps, or PowerPC apps will not run under Lion. Rosetta will not run under Lion.