Looking inside HTC Europe support web site, they write about TYTN WM6 update:
31/07/07 - Windows Mobile® 6 upgrade for HTC TyTN
HTC has made a Windows Mobile 6® OS upgrade available for users of the popular HTC TyTN device.
The TyTN becomes the first HTC device to get the upgrade, with the HTC P3300, S620 and Advantage also scheduled to receive the upgrade from August.
HTC TyTN users can download the Windows Mobile® 6 upgrade exclusively from the “My Downloads” section of HTC eClub.
Registration to HTC eClub is easy and completely free… so if you aren’t already a member, sign up today to keep in touch with a range of benefits.
They are not talking about P4350....