AH! Well, there is no doubt at all that DreamHost oversells, but that is not necessarily a bad thing. It is what allows you to have the level of service that you enjoy at the prices we offer. For a good explanation of how all that really works, check out our blog post:
In fact, for more discussion about "hits" and "traffic" and PS vs shared, you might also find this interesting:
In that last one, you will see that the problems from "high traffic" dynamic sites are not likely to be caused by human visitors at all, but rather by bots (hence the need to fire up that cache!).
If you take those figures in the post you referenced above, given our quad processor machines, you will likely find your server running in good shape load wise the great majority of the time (of course, there are exceptional transient spikes). It's all about the trade off between resources and value, and what we try to do is give the most possible performance for the smallest amount of money feasible. For the great majority if sites, this works very well, for others, there are PS servers, which give you many of the advantages of a dedicated box at a fraction of the cost.
--DreamHost Tech Support