There seems to be two acceptable ways of delimiting three or more items in English. The difference being in the amount of commas.
One, two, and three.
One, two and three.
In the past, I noticed most people using the the first type, and some "professional" articles using the second type. However, more recently, I have seen the second type much more often.
This could either be due to what I have been reading, or a change in peoples' preference. Has anyone else noticed this phenomenon?