I know I should be happy that App Engine will bring up new servers when the demand arrives, but all I can think about is watching the meter spin when an errant query starts chasing down data on other servers. Getting wildly popular may turn out to be more of a nightmare than a dream because Google will dutifully roll out more versions of your applications, burn more megacycles, and put it on your tab. I'm sure Google will come up with ways of limiting the size of the bill, but all I can think of is firing up a slick Web site and repeating Woody Allen's line from "Manhattan": "God, you're so beautiful I can hardly keep my eyes on the meter."

The Bottom Line Google App Engine preview release Google, google.com/appengine Preview   Cost: The beta program is free but closed to new members. Applications are limited to daily quotas such as 2,000 e-mail messages, 200 million CPU megacycles, and 2.5 million data store calls. The documentation suggests that users will be able to spend money to expand the quotas. Platforms: Any Python 2.5 Web application that operates in a sandbox that excludes actions such as writing to the file system. Google has integrated several standard Web frameworks to simplify the development process. Bottom Line: Google App Engine hides the grime of deploying a scalable application to a number of servers. The limitations on the sandbox make this "cloud" best for dynamic Web sites that act as a relatively thin layer of business logic sitting on top of a data store. Google's Python/Django framework makes developing simple applications quick, and the database structure encourages scalable design by excluding joins. On the downside, there's not much support for AJAX, porting some applications will require rethinking the database schema, and your coders better like Python, which is currently the only option. About our Reviews and Scoring Methodology

Google also lets you access Google accounts, the creepy feature that links your search history with your Gmail account. The users of your application don't need to set up a separate log-in or a separate account. You can get a user object with all of this information when they show up, if they've recently been logged in to read their Gmail. If you don't want to use this feature, you could always spin up your own user accounts with the database, of course.

Some of the FUD spread by rival camps suggests that Google just wants to use App Engine as a way to nurture Python developers so that the company can hire them away. Others see it as a cynical way to gain control and lock people into their Google accounts. Others think this is just a technique for Google to build a big plantation with you, the Python developer, toiling away to monetize its app cloud and add more value to the Google account.

Tenant's rights
That's all just a bit too cynical. While the terms and conditions include a number of scary phrases giving Google the power to do pretty much anything with your baby, they seem like rational responses to the scary prospect of letting anyone put applications on your cloud. Copyright violations, spammers, and pornographers must keep the lawyers at Google up late at night. The lock-in is a real problem, but it is mitigated a bit by some of the open source licenses. Python and Django are pretty much free if you want to take your application and run with it. The hurdles and caveats are annoying, but the App Engine formula seems like a serious play for the low end of the marketplace where small developers create niche applications.

The service is best for the simple applications that plan on staying simple for the time being. While the cloud's ability to scale the application quickly is a nice feature, the limitations of the service should be constraining for anyone who has big dreams built on complex code. The sandbox offers only limited services, and the legal issues are still new. While the Google lawyers did a pretty good job of anticipating many of the potential potholes for the service, that doesn't mean they can go away. Google reserves the right to "pre-screen, review, flag, filter, modify, refuse or remove any or all Content from the Service." Will Google be a good hosting provider and treat the small fry like a partner, or will it just nuke entire applications when a DMCA notice shows up? Time will tell.