I think it definitely has!
I've learned a lot about famous and not-so famous jazz musicians on the internet. Sites like this one and the ex-mp3.com have vast knowledge on the jazz music scene which would otherwise be much harder to acquire. It's very easy to stream a song for you to judge music like at mp3.com and it's easy to discuss various musicians and music styles on sites like this. Without the internet I think jazz would be far less understood and popular than it is.
I also think the internet could have a negative side in that it may be too free and easy a way for musicians to express their music, hence a lot of garbage music associated with jazz yielding a bad-rap image. If you listen to some of the upcoming musicians that classify their music as jazz-style, some have very little quality and skill to their music and are around longer than if they had to make live auditions and performances like jazz musicians of old had to do. I guess I'm trying to say that the internet lowers the 'weed-out' filter that musicians had to deal with in the past.
Overall though, I think the easy accessible information and music far outweighs the 'too-free' point.