Update: an important fix was made to the 64-bit version. Please use this manifest path:
As I just posted over on the PANTHEON drupal group, a new release of Project Mercury is out, now including Apache Solr as the search back-end! This is especially exciting because it rounds out the core technology stack for a best-practice "all in one" server. Mercury not only delivers high performance Drupal out of the box, it's also got all the pieces you need to scale your architecture vertically when the time comes.
If you want to snag the latest version, search EC2 for "mercury" and jump on the alpha-6 AMI. It's available in 64 and 32-bit flavors both in the US and EU hosting zones.
With the major stack pieces in place (or so we think; let us know what we might still be missing...) the focus will soon shift to stability, tuning, and portability — aka alternatives to EC2 — as the project enters its Beta phase. This can't come too soon: we've already seen more than 100 instances launched since the last (0.51) release, and more and more people wanting to run existing sites using Mercury as a host.
To that end, we're actively researching options to provide the whole stack as a pre-bundled install with more traditional VPS providers, and hope to solidify some working partnerships going as we move into the Beta phase. We're also going to be working on documenting the heck out of the basic tasks of putting an existing site "onto" a Mercury install, creating an install profile for people starting from scratch, and making the base stack available in other cloud-friendly forms (e.g. VM images, Rackspace images, etc).
As Mercury matures, the rest of the PANTHEON project will start to see more updates. Mercury is the "hosting" piece of the puzzle — and will eventually be broken down into dedicated images for each piece of the stack — while Vulcan handles development/testing, and Aegir takes on deployment. There's a lot more to be added to those steps as well.
It will be a while before we have all of this working together, but we've been very encouraged by all the positive feedback. We believe we can help propel the next wave of Drupal growth by making Best Practices in every step of the project cycle — build, deploy, scale — easily available to as wide an audience as possible.