I've been doing some testing of Moodle 2.0 on Amazon Webservices, EC2 and RDS. You may be interested to read the results. I'd also be interested to hear from anyone successfully running Moodle on AWS.
For those who are interested, there are install guides in Moodle docs:
I am using instance of moodle 2.2 on cloud..
I have 2GB of RAM on amazon cloud, but moodle is running very slow, can you tell me minimum space requirement to run moodle efficient on cloud?