Random Question Inspired By My iPod's Shuffle Feature

When John Lennon thrice sings, in "A Day in the Life" (from Sgt. Pepper -- and not any of those fancy re-mixes either, just the good old-fashioned CD release from 1987), "I read the news today, oh boy", how are we to understand those last two words? Is it a simple groan, or is it sarcastic glee? What struck me is how both meanings would fit equally well with the rest of the song -- the worldweary overwhelm of Lennon's newsreading.

Indeed, I can't quite make up my mind whether there is in fact any difference between those two options, or whether something said with sufficiently sarcastic glee might as well be a groan.

Perhaps one way to capture the difference -- if there really is one -- would be two possible punctuations of the line:

I read the news today (oh boy)
I read the news today -- oh boy!

Any thoughts?