She did a terrible job using / teaching her audience about it, and all the moms at home give it a shot, don't get any value out of it, and quit.
Not to single out just Oprah, celebrities in general have done a great job decreasing the value.
So I deleted my account and now use specialized searches through the API to just show me what my close friends who use twitter are up to.
I don't buy that.
If anything the uptake I see in Twitter is nearly ALL people nerds would describe as "not tech-savvy." The nerds I know are all haughty and dismissive of Twitter. Most of the people I know on Twitter do not work in the tech industry, nor are they programmers or any other type of self-described "tech savvy" person.
At this point in history I'm not sure if it still makes sense to brand anyone as not tech-savvy enough to use something on the internet. Everyone in the developed world uses the internet all the time. My grandma has used email for 15 years. My mom has an iPhone and is in charge of curating her work's wiki. My 16 year old cheerleader cousin is on FB, MySpace, five IM networks, sends 4000 text messages a month, etc. The us vs. the not-tech-savvy attitude is a bit archaic at this point.