New Rails PaaS coming. Rails Ready

Raw performance doesn't matter to me much as long as I can handle enough concurrent requests, and serve as few as possible with Rails (and trust me, I've built and maintained a webapp handling 50k+ concurrent connections). A good N-tier architecture goes a long way. You'll want a solid HTTP cache, an easy path towards integrating a CDN (better if you can resell and my IT dept has fewer vendors to worry about), and of course memcached is useful.

Creating an easy deployment process can be difficult but you'll find a good solution. No doubt you'll have a decent web management console as well. Devote some time as early as possible to the non-functional parts of the platform (fault-tolerance, availability, security, customer service and relationships) and you'll be in a good place.

Best of luck!

Heroku deployment shell script is nice. Minus is that workers are too expensive -- you pay a full one even if you only use it rarely. Scaling solutions like SimpleWorker can't access their shared database, so you have to upgrade to a super expensive one or develop work-arounds.

Not trying to start a hype machine. Please let us know what you do and do not like about the existing Rails hosting providers out there and the offerings they have. Your input is key :)

Performance. Whether that is through a better VM (Rubinious?), faster gear, whatever, your worry not mine.

Ruby 1.9.2 has significant speed improvements over the 1.8 vm