This is my only simple innocent quest. Gnome 2.3 seems to be absent from CentOs repos and gnome devs say it would be one royal pain in the a$$ if i tried to build it from source. any suggestions ?
I think you mean Gnome 2.30 (just released).
Installing the latest and greatest version of Gnome on Centos would be a massive undertaking and really defeats the purpose of running Centos to begin with. Centos (and Red Hat Enterprise Linux) is focused on a stable, predictable set of packages that will be supported long term. It is absolutely not focused on having the latest and greatest software and being a hotbed of innovation (Fedora serves that purpose in the Red Hat ecosystem).
In fact, as of this writing I do not believe any distro is shipping the final release of 2.30. If you must have it right now, then you probably want to look into Foresight Linux (it is usually the first to push Gnome updates to stable). Barring that, you could look at the Beta releases of Ubuntu and Fedora as both are expected to ship the latest Gnome in their next release.