This article implies that only people sharing music files on their hard drive over the internet are in danger of RIAA lawsuits.
This would explain how the "blogspot listing a Rapidshare link" sites stay immune from the RIAA. The blogspot says "hey it's on Rapidshare, it's not my hard drive". Rapidshare can say "hey what a user puts on Rapidshare is their business". Either the blogspot user or Rapidshare will kill the RS link if someone associated with the shared album complains/asks.