It is still recommended by the majority of American style guides. Some people think the Oxford comma is redundant, since you are already saying "and," which is kind of the same thing as a comma in itself.

I would say a good rule of thumb is to use it, particularly when it helps you avoid ambiguity. One example of a sentence that benefits from using the Oxford comma is "I want to thank my parents, Eric, and Molly." Let's say Eric and Molly are your siblings. If you take out the Oxford comma it will seem like they are your parents: "I want to thank my parents, Eric and Molly."

English constantly changes over time.  We have to suffer through these punctuation and grammar "trends".  Is the Oxford comma hip?  Is it out-of-style?  Word on the street is that there are two schools of thought about the Oxford comma.  You can use it if you'd like, or you can decide it's not your style.  

I like the Oxford comma, however.  It shows finality at the end of a list or series.  It adds emphasis and a sense of conclusion.  I always err on the side of voting "yes for the Oxford comma!", but certain teachers or professors might say, "You don't need to use that anymore."  This is a time when you can ignore them, though.  The SAT still upholds its use.  Style guides still uphold its use.  

Just decide early on in a paper or a piece of writing whether you are pro-Oxford comma or anti-Oxford comma, and stick to it!

All language is in transition over the course of history, and we can observe such a transition with the Oxford comma. Magazines often follow the style that it's best to remove any comma that is unnecessary for clarity. Someday, this standard may become an American English convention, but for now, the two options are equally valid.

I agree with the previous answer: it's best to use the Oxford comma to avoid ambiguity (and there are many writing situations that would support this), but as you decide whether or not to use this traditional English comma standard, you should always follow the assignment's leader (teacher, boss, school standard, or specific instructions), so if you get a job at a magazine, you may find they won't use the Oxford comma.

On the SAT, you will find that the Oxford comma is used, but the test writers avoid testing specifically on rules that are in nonstandard or in transition. So, the SAT tends toward the Oxford comma; however, at least for now, you won't be specifically tested on that.

One more thing to consider: even though you may find the Oxford comma is optional, it's important to be consistent throughout a paper. "Optional" does not mean you may choose which rule to follow for each sentence.

There is STILL a place for the oxford or "serial" comma.  In most cases, the "and" takes the place of the comma.  HOWEVER, if you don't include an oxford comma, some things could actually be implied:

1) a list being taken as an aside

As the old joke goes: "we invited the strippers, jfk and stalin."

here, there is an ambiguity.  one reading of the sentence could mean that the streppers WERE jfk and stalin.

2) another possibility is when the last two (or any items) of the list are combined by a "and" without using a comma.  The ambiguity occurs because the items linked by and could be compound nouns "eggs and bacon" as if they were "one item".  

It's a COMMA!  include it for clarity's sake!

1.  It saves ink which is important to those involved in major publishing.

2.  It saves space which is also important to those involved in major publishing.

3.  The sentence still makes sense without the comma. 

Perhaps it went the way of saying "why" instead of "how come"!