Um, while you're closer to being correct than Fudbucker (dying declarations have no
special significance that causes a court to treat them with extra deference), a dying declaration still means that the witness is unavailable, and therefore, all the
standard rules for unavailable witnesses listed in FRE 804 (which is a superset of general list of exceptions to the hearsay rule listed in
FRE 807) apply.
So technically, you guys are both wrong. Dying declarations are neither treated specially, nor automatically dismissed as hearsay.
eta: two of the most interesting exceptions are: 804(b)(2), which basically covers testimony from someone who is dying
about the cause or circumstances of their death and 804(b)(6), which covers testimony against a party who wrongfully
made the witness unavailable (a way to deal with witness-tampering).
eta x2: on the other hand, absolutely nothing in the FRE would give any extra credence to a dying declaration about
the existence of little green men! (Unless they were the cause of death.)