Never got in to Cloud Foundry because it's overly complex and very limiting. Always went with Heroku, but wished I could have a Heroku-style infrastructure on the above mentioned VPS providers for the benefits of running better hardware, being more affordable, being multi-region, etc, etc.
Digital Ocean: http://kencochrane.net/blog/2013/06/running-docker-on-digita...
Rackspace: http://kencochrane.net/blog/2013/05/running-docker-on-racksp...
Linode: http://stinemat.es (site seems to be down at the moment)
Don't see Linode listed there, but between that or Jclouds (http://jclouds.incubator.apache.org/documentation/reference/...) you have like a billion cloud API's available to you. I imagine teaming one/both would make Flynn a very interesting alternative to Cloud Foundry/etc.