Actually I'd prefer a half a cantelope or an espresso as opposed to a cookie thanks lunabyte.
With ec2 you can basically get a 1.7Ghz x86 processor, 1.75GB of RAM, 160GB of local disk, and 250Mb/s for $72 per month plus $0.18 per GB bandwidth. (Data transfer backup to S3 or within ec2 is free)
The cool thing is is you can back up your image to s3 amazons storage service. It takes a few minutes to launch a completely new instance. You only pay per hour for each instance. 10 cents per hour. So if traffic is busy on thursdays and fridays you can launch additional machines for those days then close them down for the quieter days.
My main reason for posting this was so that people with only basic computer skills like myself know that its reasonably straight forward to do a set up on ec2. I'm not offering advice here just info that some people might find useful.
Lunabyte, I'm guessing that your skills and ability are better than 95% (if not more) of people that try and do a wpmu set up in any form.
Anyway I found it easiest to use firefox ec2 ui to manage instances. If you're using windows I used WINSCP and putty for access.
So here's more info:
1. It's probably easiest to use the public ami Fedora 4 image with webmin/virtualmin installed
2. You'll need to install phpMyAdmin
3. Get the ip details of your instance from virtualmin under whatever virtual server you're going to be running the wpmu install from
4. Rather than setting up a nameserver I just used zoneedit.com for dns. You can stick some info in your local start up script - for more info visit here:
http://www.ioncannon.net/system-administration/120/dynamic-dns-with-ec2-and-zoneedit/
5. For info about setting up wpmu on Apache2 check here:
http://mu.wordpress.org/forums/topic.php?id=2782&replies=8#post-16714
6. The fedora image with webmin/virtualmin has php.ini memory_limit set to 8mb or something so you'll need to change it to 64mb or whatever
7. You might also need to change your /var/named/chroot/var/named/yourdomain.com.hosts files to add the line
*.xxxxxxx.com. 14400 IN A xx.xx.xx.xx
Hmmm I did that in zoneedit.com.
Once you've got everything working back up your image to s3 and then register it with firefox e2 ui.
Use these commands to bundle up your image then send it to s3, then register it so that its available for instant relaunch in your private ami's:
http://docs.amazonwebservices.com/AmazonEC2/dg/2007-01-19/bundling-an-ami.html