Sorry to bring this back after so long, but I've just read it, and cannot refrain from commenting. U. & o. may be frequently used interchangeably, but IMHO they shouldn't be; certainly not in all cases. I agree with the go/be folks. Wsieber gave one good example of how they are different. Here's another ex.: my concern about my weight is omnipresent; it is not ubiquitous. I hope that eating only things that are good for me will soon be ubiquitous; but they will not be omnipresent, because I do not eat every minute of the day. Another: our city buses used to have ads that read "TARC {Transit Authority of River City} is ubiquitous". I'll grant them that they were, for the sake of argument. But they were not omnipresent: you could not see one 100% of the time you looked for one.