This article discusses what Billy Bragg said. The writer makes quite a good case for Billy's analysis being somewhat incomplete and to some degree rather fanciful.

Discussion of the Billy Bragg NYT Article

Featuring 4 of your songs on your MySpace page is hardly likely to dent your sales. Well unless your perforrmance is SO bad that it warns potential buyers off your CD. It is much more likely to send people off to buy the full thing, or if you've been crafty and put up tracks from 4 different albums and not just your latest, 4 full CDs.

Likewise the iLike application on Facebook (which is a LOT more felexible) even has bloody great buttons saying "buy" linked to iTunes. I notice there are a few artists that don't seem to be features on iLike, but most are, and should be getting paid either that way or by people buying CDs.

That model breaks down of course if you get a large core of people who just won't buy tracks or CDs and just rely totally on piracy. I don't think we are anywhere near there yet, because lots of people do still prefer to have the CD, the liner notes etc. However, if your potential buyer decides that the only songs you've done they like are "New England", "Englsih, Half English" and "Walk Away Renee" and buy only those, rather than whole CDs, you are going to have a much less comfy lifestyle than you've been used to! I think such "cherry picking" might well be why CD sales are allegedly falling.

Coincidentally, the Bard of Barkings latest opus (Luxury edition) has just landed on my doorstep, so I'm off for a listen.