Celebrim
Legend
Fom this article and other things that Mike has said, it seems that the tokens are a mechanism for handling non-magical resources, and also a neat way of getting around the x/day mechanism which is pretty difficult to logically justify.
I'd go so far as to say that from a gamist perspective, there is no difference between 'magical' and 'non-magical' resources. In effect, tokens allow you to cast what are (usually) 'non-magical spells'. At high levels, you'll note that even Mearls was scrambling to find mundane justification for the spell effects. It would be completely possible to make magical classes that expend tokens to cast spells, and in fact my guess is that Mearls will do exactly that. The WotC class that seems most similar in concept to what I now believe the Iron Lore classes to be like is the Warlock from CA.
I think that the tokens are probably more of an attempt to get somewhere between the 'at will' of feats and the 'once per day' of spells than they are away to get around x/day mechanism itself. In fact, just from the previews we've already seen one trait (at least) that offers 'once per day' bonuses. The Warlock suffers from his ability to do things at will, in that its very hard to make at will powers fair. By making them tokens, you let every character cast small spells every round in an encounter, or one or two big spells per encounter. Or to look at it another way, tokens let you balance having lots of feats by only being able to turn on X number of them in a given round.
Exactly what happens when - as they often do in many situations - one encounter flows into another one in long running battles is not completely clear. Reinforcements are the bane of Iron Lore characters. Perhaps encounters 'refresh' as soon as new groups arrive.
Once you realize that tokens are spells, you realize that they are going to be infinitely extendable and intertwinable with feats. At first that sounds like a good thing, but I wonder just how much more detail D20 can handle. I'm a former GURPS player. I know too much of a good thing when I see it, and all these 'spells' from every character nearly every round combined with more feats and situational abilities seems like too much of a good thing. I think you'll start drowning in calculations as everyone is essentially casting spells every round (and most of these are spells that generate fluctuating buffs), and deciding (as it where) which of their myriad feats that they are going to choose to use this round.
The system would work better for me if they removed it from a battle map and abstracted the combat a little. That way you could have the sort of cinematic combat where characters were actively shaping the world details in the way that the rules seem to encourage without getting overly bogged down. Whether or not that is actually a simulation of a 'gritty low magic' world is another matter entirely.