In conjunction with its annual developer conference, Google on Tuesday released App Engine 1.5.0, an updated version of its cloud platform service, and promised new enterprise-oriented features later this year.

At the same time, the company is doing away with Google App Engine for Business, which was launched last year at Google I/O 2010, as a separate product. Google wants App Engine to be seen as a viable product for enterprise customers.

After three years as a "preview" product, App Engine is expected to reach a level of stability and maturity sufficient to graduate from peview status during the second half of 2011. More than 100,000 developers use App Engine every month, and it supports 200,000 active apps that deliver more than 1.5 billion page views every day.

Based on feedback from business customers, Google has come to understand that per-user, per-app pricing is not the right model for many business customers and that the preview designation keeps companies from committing to App Engine.

When the service loses the preview stigma, Google expects to provide App Engine customers with enterprise features: a 99.95% service level agreement, operational and developer support, billing via invoice, a new terms of service agreement designed for business use, and a simplified pricing structure.

Greg D’Alesandre, senior product manager for Google App Engine, explained in a blog post that these changes demonstrate Google's long-term commitment to App Engine and bring with them a policy that guarantees support for deprecated APIs for three years, to ensure that apps written using outmoded code continue to function during this period.

Dan Murray, co-founder and managing director of WebFilings, a company that provides cloud-based SEC reporting capabilities, voiced approval of App Engine's graduation from preview status during a developer tools media event on Tuesday afternoon. "We're very excited that the product is leaving preview mode," Murray said. "It really validates our early choice of App Engine."

The App Engine update introduces a capability called Backends, which enables applications that run for long periods of time or require high memory allocation.

It also features an improved version of Task Queues, by which automatic tasks can be scheduled for execution in the background. The new Task Queues feature makes App Engine able to better communicate with other on-premises software through the use of new REST-based APIs.

Finally, App Engine 1.5.0 introduces support for Google's Go programming language, which is designed for coding scalable cloud applications that utilize multiple processors. App Engine also supports Python and Java.

In other developer-related announcements, Google opened Google Storage for Developers to everyone, made its Prediction API available to everyone, and released version 2.4 of Google Plugin for Eclipse, with Android and App Engine project creation templating, cloud-to-device messaging support, and RPC boilerplate code generation.