MEDIA IS, MEDIA ARE
In response to the aside at the end of my post below, Rocky Mountain News editorialist and syndicated columnist Linda Seebach (another former Angeleno and self-described "refugee from the linguistics department"), writes:
Yes, "media are," in isolation. But there are other grammatical patterns pushing it to become, like "opera," an English word construed as singular.
One is its frequent use as an adjective, e.g., "media bashing." English adjuectives don't inflect, so when a noun is used in an adjective slot, it is used in the singular. We say, "most journalists are college graduates" rather then "most journalists are colleges graduates" even though there are obviously multiple colleges involved. But there's an exception to the rule, for English nouns with irregular plurals, such as "woman." People write, "women entrepreneurs," not "woman entrepreneurs," although they are quite likely to opt instead for "female" because neither the singular nor the plural sounds quite right.
Over time, languages tend to flatten out irregularities. "Media" is very commonly used as an adjective. Furthermore, the singular is really quite impossible: "Bloggers indulge in a lot of medium-bashing" (too many other possibilities - psychics? a fondness for extremes?). So people are constantly hearing "media" in a slot they know (not consciously) is reserved for singular words, and after a while it starts to sound singular.
I don't believe I've yet seen "medias" (as an English plural, not the Latin word) but I could see it happening, first as a neologism in a context where many different kinds of media were being discussed (as with fish and fishes). "To win an election, you must master all the different medias" and eventually without notice, as with operas.
Oddly enough, all the educrats seem to have settled on "criterion-referenced" for their favorite kind of test, even though few of them seem to know in other contexts that "criteria" even has a singular.
I have indeed seen "medias" used as the plural. To read Linda's column on blogs, click here.