As Google's Nexus One smartphone celebrates its one-month birthday, word comes that Mountain View has sold a mere 80,000 of the devices.

But if you believe Google's mobility chief Andy Rubin, that number is just fine with him.

When Google's self-described superphone was released, Rubin told GigaOM's Om Malik that he thought Google would sell, "at the very least," 150,000 Nexus One phones - a statement that Malik mildly modified after the phone's 20,000-sale first week to "be happy to sell about 150,000 Nexus One devices."

Rubin was talking about total Nexus One sales, not first-month sales, and so the Googlonian cup is now either half-empty or half-full.

That 80,000 estimate comes from a Dow Jones report citing data from the mobile-market analysts at Flurry, which contrasted the Nexus One sales with the iPhone's 600,000 first month and the Motorola Droid's 525,000.

But those comparisons are off the mark. Both Apple and Moto marketed the bejesus out of their phones - the Droid campaign, for example, was reported to be juiced by a cool $100m. Google, on the other hand, is satisfied with free media buzz and word of mouth to get the word out about the Nexus One.

Plus, the Google phone is sold solely over the web.

That said, the Googlephone's first month hasn't been without its sales-squashing bumps. While Mountain View struggles to get its customer-service ducks in a row, for example, it has found itself beset by a chorus of customer complaints.

There have also been gripes about spotty 3G performance, and the bad press engendered by a US Federal Trade Commission probe into carrier T-Mobile and Google charging double-dip early termination fees.

In fact, that 80,000 figure may be high. It's based on phone usage, and many of the Nexus One phones out there belong to Google employees who received them in late December as a free gift from the company. Google has about 20,000 employees.

All this merely underlines the fact that Google's "superphone" is a test case, an experiment in selling phones online in a store that, as noted during the phone's rollout event, will be joined by Verizon Wireless, Vodafone, Motorola, and - Google hopes - others.

"The Nexus One is simply the first of a series of examples where you can essentially purchase a phone online from one or multiple manufacturers and have it just work," said Google CEO Eric Schmidt. "We think that's a natural evolution of a particular model."

And those phones will run Android and they will feed Google's ad-juiced business model. As Andy Rubin noted during the Nexus One roll-out: "If you want the best possible Google experience, you'll come to the store, grab the device, and [the Google] advertising model takes off."

Jump-starting that "Google experience" through the sale of 150,000 Nexus Ones is a smart business move - especially when you don't spend $100m on advertising. ®