HTC is also committed to offer Windows Mobile 6 upgrades for the most recent and popular devices in its current range. This includes recently launched "messaging" products, which will enjoy the greatest benefits of Windows Mobile 6, including the HTC Advantage (aka HTC Athena), the HTC TyTN (aka HTC Hermes), the HTC S620 (aka HTC Excalibur) and the HTC P4350 (aka HTC Herald). The upgrade will also be available for the award-winning HTC P3300, plus some of the operator-branded devices. The upgrades will be rolled out from June, in line with the operator partners' strategies. You'll be able to find the latest HTC-related releases as they're made available at:

the::unwired で知りましたが、htcは自社ブランド端末(英語版)のWM6へのアップグレードを公式に行うと発表したようです!
対象になるのは、HTC Advantage(HTC Athena),HTC TyTN(HTC Hermes),HTC S620(HTC Excalibur),HTC P4350(HTC Herald)の4機種になるそうです(^^ゞ