Currently PlexUtilities is nowhere available for download. If Plextor follows their usual way, the original will only be distributed with drives while updates only will be available on their web page.
As for what exactly PlexUtilities will be, here are some guesses:
[U]Plextools LE[/U] renamed and extended with the necessary code to handle the new drives. This would IMHO make sense since PlexUtilities offers much the same of what is announced, for example for Q-Check functionality. So why do all new code when much of it is already in place? The new name might be to distinguish against the commercial version that Plextools XL was.
An updated and enhanced version of [U]Kprobe[/U]? Seems unlikely since Kprobe is very much stagnant when it comes to functionality. Also Kprobe was never an official liteon offering AFAIK.
An updated and enhanced version of [U]DVDScan[/U] 0.04? This one looked very promising but sadly never saw further development.