Oh definitely. Not all fantasy is mythological in nature. And there are even distinctions there: Tolkien's work is obviously mythological in nature, but isn't directly drawing on real-world myths. By that, I mean, our myths and legends (Nordic, Celtic, etc.) may be present in the mythology he created, but his characters are only familiar with the mythology of Middle Earth, not earth myth. So I'd consider that mythopoeic, which would also be true of, say, sartorias's "Inda" novels, or Terry Macgarry's (sp?) Illumination and its sequels. Any world that has a distinct cosmology that actually matters to the characters and ties into the story probably fits into that category.

Most of the novels that I read inside the fantasy genre that make use of earth myth are in the contemporary or urban fantasy sub-genre--because they deal with the "real world" rather than a high-fantasy setting. Quite a few of them are YA. ;)