The case for the Oxford Comma in one screenshot...

[Playinghardball]

[mike_c]

1. LOL....

Nice catch, Hitler.

[Le Taz Hot]

2. I never knew that had a name.

[PCIntern]

3. Most interesingly,

the wiki entry on Oxford Comma has a funny situation which arose in the Times and involves, Mandela and Peter Ustinov!

[Hissyspit]

4. Well, TECHNICALLY, that's not a sentence.

So it doesn't really make the case completely. But I mostly agree with your sentiment.

Also, it's funny.

[rock]

10. Not a sentence

But "headlinese". Neither are these.

[Hissyspit]

13. Have you got some kind of hatred for semicolons?

[rock]

16. Nope

[eppur_se_muova]

5. "The biggest influences in my life have been my parents, Mother Theresa and the Pope."

Saw something very similar to that on DU some time back.

[Spider Jerusalem]

6. "I'd like to thank my parents, Ayn Rand and God"

plenty of examples, some of them even real ones!

[alcibiades_mystery]

7. OK, I'll do the obvious (bicycle)

[TxDemChem]

8. My husband knows that I LOATHE

That damn Oxford comma. However, point taken.

[moondust]

9. Is there a coherent case against it?

Too much work to hit that extra key?

[Hissyspit]

12. Yes, sometimes it's not needed and is distracting to the reader.

What is the ideal use is that people be smart enough to use it when it is needed and not use it when not needed. But, well, you know...

[moondust]

14. Distracting?

Can you cite an example of it being distracting?

It ALWAYS separates one item in a list from another, just like the other commas in the list, and thus ALWAYS clarifies the meaning--the same as the other commas.

[mulsh]

11. The nuns who taught me to write said "just do it." and I"ve been using it ever since.

n/t

[calimary]

15. You've heard of that writing exercise... "woman without her man is nothing" ?

How important is the placement of the humble comma?

A teacher asks his students to punctuate this sentence: "Woman without her man is nothing." The men all write, "Woman, without her man, is nothing." The women all write, "Woman! Without her, man is nothing!"

I kinda like the second version myself...

[Android3.14]

17. Couple of things

It's not the comma. It is the passive voice.
One, editors should avoid passive voice in headlines.
Second, it's the passive voice that makes the comma use funny. If it had been "Top stories: World leaders at Mandela tribute, Obama-Castro handshake and officials set same-sex marriage date" few would have noticed the double entende, because the use of active voice eliminates the chuckle.
Third, the AP Style Book says to use the "A,B and C" format for simple lists, but to use "A, B, and C" for clarity in more complex lists, and to use the semicolon in extremely complex lists. An observant editor would have used the additional comma.
The comma debate, like the debate over passive voice, is more about recognizing when to use it and when to decide against it. The editor in this case, was paying little attention.
But news editors must deal with many thousands of words each day, and the unedited content must leave within minutes of hitting the editor's desk, so I'm gonna give the dude or dudette a pass.

[bluescribbler]

18. Does Michelle know?

That's gotta be a shock to her and the girls.

[Ratty]

19. Now you made me go to Wikipedia

Fascinating article with lots of fun examples. I recommend it.

http://en.wikipedia.org/wiki/Oxford_comma

[merrily]

20. Where are they registered?