Open Cloud Manifesto, Cloud: commodity or proprietary, Portable Cloud Computing, AppDrop all deal with the same problem.
Problem: The problem is that cloud providers are offering different clouds that differ in basic interfaces and level of access to underlying components. For example, Amazon's services are bottom up (here's a CPU and storage, now install your own software and use the components you need) and Google's is top down (write some code to these APIs and we'll scale it for you). One’s application code becomes dependent on a particular vendor.
Once an application becomes sufficiently complex, moving it from one cloud to another becomes difficult, placing folks at the mercy of their cloud provider. Cloud providers have every incentive to develop proprietary APIs in order to lock folks into their services. Also, moving lots of data between providers may make this difficult or expensive to do in practice (data inertia).
This is in contrast to most web applications today. The LAMP stack allows one to build vendor-neutral applications from free parts and select from a competitive, commodity hosting market.
Solution: The Open Cloud Manifesto goes over several challenges to cloud adoption, such as the portability and interoperability, that must be addressed through open collaboration. It suggests that this is the right time for industry participants to work to ensure that innovations should be guided by the principals of openness so that customers will feel confident in building their applications to run on cloud providers.
AppDrop is a container for applications developed with the Google App Engine SDK, to run entirely on Amazon's EC2 infrastructure, and they work without modification. However, this simple portability comes at the cost of scalability. The App Engine SDK doesn't use BigTable for its datastore, instead relying on a simple flat file on a single server. This means there is no scalabity, but for apps with limited resource needs, something as simple as AppDrop would work (of course, scalability is a primary reason for using a cloud).
Hadoop provides a lot of the building blocks for building cloud services. Its current focus is on batch computing, but several of its components are also key to cloud hosting. HDFS provides a scalable, distributed filesystem. HBase or Couch DB provide a database comparable to Amazon’s Simple DB and Google’s Datastore API.
Future Influence: The open-source community will likely play a significant role in interoperability and migration between clouds. Also, in order to take market share from competitors, cloud providers may build APIs that allow application builders to more easily move. AppDrop is a basic start. Amazon may consider building on this to more effectively tie in the Google App Engine API with Amazon's underlying services in order to provide the same scalability.