What the "F" is White Guilt ?

Recently, I was browsing different sites and blogs just to see who was saying what. I stumbled across a community on a blog site dealing with "White Guilt" Is this an actual phenomenon or is it the latest trendy new age malady? Did/do you own slaves? Did/do you oppress minorities? In my opinion, this is just the new mantra for white Obama supporting, "one of my best friends is Black" stating, Kanye West loving, Roscoe's Chicken-n-Waffles eating, well intentioned but ultimately condescending liberals.
My other question was "What/Who is White? (Capitalization intended) When did those people become white? Are Jewish people white. Are Italians white. Are Irish people white? What about the Spanish (from Spain)? I read an article about the problems Italy has with the Roma. From an American point of view, Both of these groups are Italian. Are the Sicilians, Italian? Aren't all of these groups considered to be white? How did/do the Irish make being Protestant or Catholic into a killing offense?
White guilt...Why? This is the most arrogant, self-important, and racist mind-set since..."White Trash". What the heck is white trash (or TPT)? How is it a racist statement? It implies that all whites are better by default. The anomalies are "White (or Trailer Park) Trash". What do those same people say about "the blacks"? What name or title is given them? Black, African-American if one is being polite. N***** if one is being more honest.
Barney the purple dinosaur has more credibility than the people suffering from "White Guilt". At least Barney knew that he was fake.