Although Microsoft's Azure supports open Web application standards, such as REST and AJAX, App Engine has spawned a fledgling open source community with actual FOSS App Engine components. Many of these are variations on the Google-supplied (and FOSS) Gaeutilities and provide various computational widgets that simplify App Engine development. Others, such as Nuages, cpedialog, and KGPL, are full-blown Web applications that you can run as is or use as a starting point for your own apps.
Cloud computing's caveats emptor
Cloud computing has some attractive low-hanging fruit for IT shops, but you should take care to count the cost before deploying in today's cloud marketplace. Some cloud computing risks are easily discerned: reliability, security, and performance. It's too soon to put mission-critical apps in the cloud unless you do the necessary homework to ensure adequate failover mechanisms, and that any sensitive data meets the ethical and legal standards for which you're accountable. Thoughtful preparation can keep you out of the cumulus-granite, but you should select applications that can tolerate a modicum of outages. Some will occur as a result of your own human error, but others will be disturbances in the clouds themselves.
A second potential pitfall is cost containment. Cloud providers are in the business of selling services, not aiming to minimize your expenses. It's your responsibility to closely track costs, and if you don't keep an eye on metered services, you can find a hefty bill in your inbox. Cloud purveyors don't make cost tracking easy. Amazon, for example, provides an excruciatingly detailed log of every CPU minute consumed, data byte stored, and megabyte transferred, but it provides no cost calculations for those statistics. You get a lump sum bill for each Amazon service you use -- EC2, S3, and so on -- with no detailed explanation of charges.
The second driver of unexpected cloud expense is the cloud's own ease of use. Spinning up a server -- or 10 -- only takes a minute. But servers stay spinning, and clocking dollars, until you turn them off. Third-party cloud management services like Rightscale and Elastra can automate the cost accounting process, as well as set hard spending limits. But you pay for that convenience -- a minimum of $500 per month for Rightscale's auto-scaling cloud management console, for example.
As long as you keep these precautions in mind, there's no reason not to leverage cloud services to shorten your IT hit list today.