First generation Omnia definitely won't support 3D as the hardware itself does not have a 3D accelerator chip.
Second generation, Omnia II has a 3D accelerator chip.  However,:-
1. It is a Samsung accelerator and does not use Windows Mobile default display driver.
2. It supports OpenGL ES version 2.0 which is not backward compatible to the older 1.x series.

On previous post, I have posted a link about a group creating an OpenGL 1.x compatibility layer for the Omnia II.  Still in progress and will take a while because of reason no.1, need to wait till Samsung release the API (something like a guideline) for the 3D chip so that the specific functions and features can be understood better, resulting in a nice driver.

As far as I know, SPB decided to stick to the older OpenGL 1.x because almost all WM phones are still implementing the older 1.x versions (e.g. Toshiba TG01 and HTC phones are still using 1.x).  So far phones which I only know using version 2 OpenGL ES are Omnia II, Acer M900, IPhone 3GS and SE Satio.
Due to reason no.2, for the time being its better to design a software which will work with most phones rather than a few ones until OpenGL ES 2.0 becomes mainstream.
FYI, mskip's an independent person.  Usually, companies tend not to benchmark themselves with them but create stuff and DEPEND on them to improve.  To cut it short, maintain a group of enthusiasts to keep the popularity. E.g. HTC phones in stock may already feel good but to the hardcore ppl, it is not good enough, hence the existence of xda-developer providing out custom cooked roms and constant new hacks but did HTC look at them and create better newer generation softwares, I don't think so.  Had before a HTC Touch and HTC Viva and recently used HTC Touch HD, I don't see any hige improvements in software.