oh man - I am TWITCHING...but the Yahoo! article got a couple things wrong...
first of all, it's not a "reef" - it's a "wreath" - honestly, who's on their news writing team?? (edit: my bad - it was an AP news feed. But really, does anyone take grammar and spelling seriously anymore?)
second, it's Harry Potter and the Deathly Hallows
Don't believe me? Go to the JKR official site and play Hangman for yourself.
now, as to the meaning of "hallow" in this context - methinks Harry will have to do some playing around with some "consecrated" objects - ie, the Horcruxes - "Deathly Hallows." I can't find a meaning that would make sense in this context that would be a noun, so I went looking...and this is what I found:http://dictionary.reference.com/browse/hallow