is it possible that 'deathly' is just an adjective as in death-like? and halloween being the 'veil' of death being at its weakest, is it possible that the title is just a little tidbit into the book of little importance (for example: goblet of fire, half-blood prince. both could be taken out and a small change could keep it on track)
i also found this on
www.mugglenet.com
Tentative foreign Book 7 titles
Harrypotter.nl, the Dutch publisher of the Harry Potter books, has listed Harry Potter en het Fatale Heiligdom as the working title for Book 7. This is not the literal translation of Harry Potter and the Deathly Hallows and translates as "Deadly Shrine," "Deadly Sanctuary" or "Deadly Saints." The literal Dutch translation of Harry Potter and the Deathly Hallows would be Harry Potter en de Dodelijke Heiligen.
In addition, it has been reported that the Finnish title will be Harry Potter ja kuoleman pyhimykset, which translates as "The Saints of Death."
UPDATE: Some readers have sent in some other translations of the title that are being reported by news stations/websites:
"Harry Potter und die todbringenden Heiligen" (German)
"Harry Potter et les saints mortuaires/mortels" (French, "Deathly/Mortal Saints")
"Harry Potter y los santos de la muerte" (Spanish, "Saints of Death")
"Harry Potter e l rito moratle" (Italian, "Deadly Ritual")
"Harry Potter e os Santos Mortuários" (Portuguese, "Deathly Saints")
"Harry Potter ve Olumcul Takdis" (Turkish, "Deadly Blessing")
"Hari Poter i Smrtonosni Blagoslovi" (Serbian)
"Harry Potter si Ingerii Mortii" (Romanian, "Angels of Death")
"Harry Potter i sveci smrtnici" (Croatian, "Mortal Saints")
"Harry Potter ve Hakdoshim Hamemitim" (Hebrew, "Deathly Saints")
Please be reminded that these are only tentative titles; the definitive titles will appear at a later stage
i must say, they only make the mystery more intriguing to me