Why hasn't anyone pointed out that the whole point of page 42 wasn't to set DCs but to ensure that a PCs actions were worthwhile according to his level? The other half of the DC/LEVEL chart was a damage calculation. The DC was based on the character level so that the effect was appropriate for the character level.
You don't swing on the chandelier to move over to Orcus for a basic attack at level 25. You swing on the chandelier to hit Orcus with a 3d8+dazed and prone attack.
Well, I'm not sure exactly what it is that [MENTION=957]BryonD[/MENTION] is trying to say that Page 42 doesn't say exactly...
Page 42 basically says:
Use these rules to resolve 'unusual actions', by which I would assume the meaning is "not covered by another rule and not a normal power use." If it was covered by another rule, or if it was simply using a power in the normal way it was intended, then no special rule would be needed, so this covers "other things." Note that the rest of Page 42 is cloaked in the language of Actions, which at least implies it is primarily, at least often, something that happens in combat (although the original SC rules do also have initiative and turns, but don't use the term 'Action' in a technical sense).
Next it says "Cast the Action as a Check:" This is pretty much absolute, so anything a PC tries to do that isn't covered by another rule is a check. This can be an attack or an 'other check', and each of these types uses the appropriate rules. Other can either be a skill check, or an ability check if no obvious skill applies.
Note that DCs are set either by the defense of the opponent (attack) or by the DC and Damage by Level table. The GM is NOT given an option to scale the DC, but it can be cast as easy, medium, or hard.
The rest of the page discusses damage, basically saying the Damage by Level chart can be used to assess damage based on the 'severity of an effect', and can be used to assess damage when a PC improvises an attack, with the repeatability and risk/reward dictating which type of damage expression to use (DMG1 has 6 choices here, later charts reduced that range IIRC).
I'm not sure what anyone has claimed this page includes that isn't here. I would only say that it should be taken in the greater context of 4e. PCs are to be challenged by things of a 'level appropriate' nature, so situations where level N PCs deal with much lower/higher level situations/effects shouldn't EVER come up. If they did, then page 42 is effectively indicating that the DCs are always centered on the PC's level (though damage is not, see the top of the 2nd column about that). I would consider that level 10 PCs going back to the village to do something and running into situations that were level 1 when they started are either operating under much more severe constraints if they attempt similar tasks (IE available time is much less, conditions are worse, etc.) or else these simple tasks are not the focus of the action and won't require checks (IE you can simply break the wooden door down now, it isn't going to require a level 10 easy check to do it).
I'd note that the sections of the DMG covering things like doors and objects also account for differences in level, with a 'wooden door' for example always being a low DC, which further indicates how things should work. Terrain has a similar mechanism, though it is cast more in terms of "if the PCs are higher level then the terrain will have some higher level effects/characteristics which raise the DC, make something up."
Admittedly, the writers of the DMG (and the RC as well) never completely 100% divorced themselves from either the presentation of DCs as 'sliding' or as 'fixed', and never well-articulated in an explicit way the idea that the action should scale in both narrative and mechanical terms, but this is certainly implicit in the entire nature of the way D&D (and 4e in particular) work!