Just watched a very interesting session on Cloud Computing by James Hamilton from MIX10.
http://channel9.msdn.com/events/MIX/MIX10/EX01
Really interesting about why you should use cloud computing instead of buying servers. Personally I already run my personal stuff in EC2, S3 and GAE and I will not go back to running an SMTP-server in the closet.
Also my ISP had a 10 day outage this summer and emails don’t like that ;)