I missed the part where the Tiara actually ISN'T dropped from the papal coat of arms, or at least there is confusion as to whether or not it is....
well, at least that's what Wikipedia says:
Quote
For a millennium until the reign of Benedict XVI it had been one of the ornaments surrounding a Pope's personal coat of arms. In a controversial break with tradition, on the first version of Benedict's personal coat of arms the tiara was replaced with the papal mitre. The mitre contains three levels reminiscent of the three tiers on the papal tiara.[3] This was the first such use since Pope Paul VI prohibited the use of mitres and croziers on coats of arms in 1969.[4] However the Vatican subsequently issued documents which contained Benedict's coat of arms showing a tiara, not a mitre. It is unclear whether the initial arms announced have been withdrawn, or whether it is proposed to use two alternate designs, a "personal" set of arms with a mitre, and an official "state" set of arms for Benedict with a tiara.
http://en.wikipedia....iki/Papal_Tiara