Wall Street Journal finally gave us Google Apps numbers:
Over the past year Google generated around $1 billion from the sale of Google Apps and separate mapping software to businesses and governments, said people familiar with the matter. Google said more than five million businesses use Google Apps, though the vast majority have fewer than 10 users and thus use the free version. In total, Google has said more than 40 million people use the free and paid versions of Google Apps.
We use Google Apps here at 9to5 HQ and love it. Heck, we’d probably pay for it if we had to.