Yet another opaque cloud, where a vendor uses some disingenuous language to disguise or confuse exactly how much resources you are actually getting for your money. Cores != hyperthreads. Don't get me started on "dynos" or "small", "large" and "extra large".
at least Heroku are pretty upfront about what a dyno is http://devcenter.heroku.com/articles/dynos (linked from http://www.heroku.com/pricing#1-0 )
Yeah but that doesn't really tell you anything about the underlying hardware. Your performance will vary depending on which nodes your dyno is running on. Hardware abstraction is a great thing, I just think that a little more transparency is in order.