From http://www.linode.com/faq.cfm#how-do-i-get-my-fair-share-of-... , they state that you get access to the full CPU of the box (if idle/best case), or access to your fair share of the CPU (if fully loaded/worst case). For the smallest plans this could mean 1/40th the overall CPU if under load. They only put accounts of the same size on each machine.
yeah i saw that, but still. how much is my minimum share? i scanned their site and couldn't find any hardware info, perhaps i'm missing it - maybe it's not really that important since i get to use more than the minimum if the CPU isn't maxed out.
Linode host boxen have dual quad core processors. Each Linode has access to 4 cores.
For their smallest plan (512MB/$19.95 a month), there are an average of 40 Linodes per box. So, on paper, you are "guaranteed" 1/20 of 4 cores. In reality (according to Linode staff), most host boxes are for all intents and purposes idle most of the time, so if you need to, you can max out those 4 cores.