I still maintain that the phrase "Indie is the new mainstream" is down right silly... Granted that Indie music had gained "acceptence" within the mainstream rock audience, indie bands still aren't selling mainstream numbers of records.
The better phrase to toss glibly around is "Indie is now a viable alternative".
"Indie" rock labels began making a mark on college radio in the 80s, yet the coverage was still limited to traditional print media or zines with limited distribution. The internet has definitely helped indie acts get the word out and more easily sell thier product. Gone are the days of thumbing through a zine and not having to send a mail order off for a record that sounds interesting. Or hoping your local record store could track it donw on a special order. CDBaby, Amazon, etc make albums easier to obtain. A review can now spark googling for the bands website and other reviews, so not everything is bought on a leap of faith.