Amazon just introduced new types of servers - larger ones. Until now it was a "one size fits all" model where you got half an Opteron CPU, 1.75GB of memory, and 160GB disk. Now you can get a server with two full Opteron cores, 7.5GB memory, and two 420GB spindles; or a server with four cores, 15GB memory, and 4x 420GB spindles. The new instances cost 4x and 8x the original ones ($0.40/hr and $0.80/hr).
Of course RightScale supports the new instance types. When you launch an image, you can select which type of instance you'd like to launch. However, the new machines run a 64-bit architecture and thus require a 64-bit Linux installation, meaning that none of the old machine images work on the new instances. RightScale to the rescue: we have a 64-bit CentOS image in beta called "Centos 5 64 V1_11_3" (ami-fbf31692). You can use it interchangeably with the 32-bit one. (We're producing a final RightImage today.)
With the advent of the new instance types I sincerely hope you've been building your servers using our ServerTemplates, because if you have, all you have to do is change the base image of your templates and it should run fine without any further changes. You don't have to rebuild all your images for 64-bits. The only gotchas are packages that you require that don't exist for X86_64 in the repositories, or binaries you may have attached to your RightScripts. We've had to tweak a few RightScripts to get our MySQL master and slave setup to run, but it was pretty painless and our customers have been really happy with the larger instances.
If you're reading this I'm sure you're dying to see your own website backed by two screaming MySQL servers on the x-large instances. Drop us a line at firstname.lastname@example.org.