Personally, I like the idea that Glorfindel at Rivendell is the same one from Gondolin. It does make me a little sad that he didn't go with the party; he would have kicked so much more ass than Legolas. Hell, he took on a Balrog single-handedly and won, more or less. He could have tangoed with Durin's Bane, leaving Gandalf alive and well to council the party after leaving Moria. He may not have upgraded himself to Gandalf the White, but I think that it would have been cool anyway.
Maybe it'll be on the director's cut, just to annoy Christopher Tolkien.