Want to run Hadoop in the cloud? Good news is, right about now you have some pretty good choices from major cloud providers.
1) Amazon Cloud
Amazon had an on-demand Hadoop offering, called Amazon Elastic Map Reduce (EMR) for a while. It is the oldest offering of Hadoop in Cloud.
Amazon Elastic Map Reduce
Amazon EMR Best Practices (white paper pdf)
Cost effective Big Data processing with Amazon EMR (slideshare presentation)
2) RackSpace Hadoop on Demand
Rackspace is offering Hadoop Service on their cloud environment. It is HortonWorks Hadoop on their OpenStack environment
Racksapce Big Data Cloud Offering
RackSpace + Horton Works announcement
3) Google Gloud
Hadoop now runs on Google Cloud.
Hadoop on Google Cloud
Whirr allows you to spin up Hadoop clusters pretty easily on multiple cloud environments. Right now Whirr supports Amazon Cloud and Rackspace cloud