Eh, in a way it kind of does? What I mean is I think of it as "you can pay less without" because if you get it WITH the keyboard then it matches the iPad price. If you get it without, it undercuts iPad by $100.
I don't think it is fair to say it undercuts the price - the cheapest surface matches the cheapest ipad 3 at ~$500, while apple still offers the ipad2 for $400.
The surface does offer more storage at the $500 level, but the ipad has a higher resolution screen.
I think that's fair.