Unconscious characters are helpless.
Do helpless characters get saves?
Yes.
"Coup de Grace: As a full-round action, you can use a melee weapon to deliver a coup de grace to a helpless opponent. You can also use a bow or crossbow, provided you are adjacent to the target.
You automatically hit and score a critical hit. If the defender survives the damage, he must make a Fortitude save (DC 10 + damage dealt) or die."
It's pretty clear from this that characters get saving thows when helpless.
Now, someone could argue that they could get Will and Fort saves, but not Reflex saves. However, the precedence for helpless characters getting saves is in the book. There are no rules (tmk) about helpless characters not getting saves, but there are rules for characters getting saves.
"Usually a harmful spell allows a target to make a saving throw to avoid some or all of the effect. The Saving Throw entry in a spell description defines which type of saving throw the spell allows and describes how saving throws against the spell work."
Hence, if the spell states that you get a save, you get a save. The only exception listed in RAW is if you want to voluntary forego your save and that is not the case here.
If there is no explicit rule about not getting saves under certain conditions (helpless, pinned, staggered, whatever), then you always get a save (assuming a non-"harmless" spell that allows for a save).
As for the "room to move" argument (presumably in the PHB glossary, I do not have my PHB with me), I would have to see the exact text. If it does come from the glossary, then it is not so much a rule as it is an explanation for how Evasion works, not how Reflex saves work, and I would not consider it binding. But, that's just me.
I think Li Shenron put it best:
"For that reason I really don't want to read too much into a sentence which, when talking about a specific thing (Evasion), it infers a general rule which isn't mentioned in other places..."