What is "mainstream music" in 2009?

Is there a center in music anymore? What makes a band "mainstream" today - a cover story in RS, MTV play, a Perez Hilton post? What the heck?

some combination of those things, plus actually selling a good number of cds or downloads or otherwise somehow demonstrating a commercial reach, i'd say. it's a sort of know-it-when-you-see-it metric, but it's not hard to find examples. taylor swift is obviously mainstream music. so's lily allen. beyonce. kanye. this year's grammy broadcast was probably as good a capsule of "mainstream music '09" as you're going to find.

I've recently taken to flipping through radio stations trying to determine this. Once I'm comfortable with what is being played, I'm going to try leaving the house and mingling with the common folk.

(I make a half joke because I really don't know, but it has never seemed so compartmentalized)

http://www.billboard.com/bbcom/charts/chart_display.jsp?g=Singles&f=The+Billboard+Hot+100

I really did listen to a variety of radio station on Friday, because I am very out of touch.

This is a very conservative radio market here, but for new music, I heard

rock - Nickelback, Papa Roach
MOR - Rob Thomas, Hinder, female songs I didn't google.
rap/modern R&B - (I googled these to find the artist) T.I., Ne-Yo, Lil Wayne, the "I broke your windows" song.
interesting Spanish language stuff, but the language barrier is ultimately too great for me.
a ton of "oldies" from the 70's to early 90's.

I don't have any conclusions, except I like the big ballad big production modern R&B tracks on initial exposure.

the "I broke your windows" song

this is jazmine sullivan - "bust your windows"

it's okay but her single before it "need u bad" is a classic

Kings of Leon?

This I broke your windows song?

If a recent song is familiar for an average 10-11 year-old, then it is mainstream. Otherwise, not.

(which is why indie, or other album oriented genres, cannot possibly be called mainstream)

The new Yeah Yeah Yeahs single is playing on the most commercial radio station in my city.

The music world is very flat these days.

Maybe in your city. I can't imagine DC101 in Washington playing it.