I don't think it'll change much, at least not at first. Later on I expect they will try to use it to push their broadband (ADSL) service with streaming media.
Hopefully BT won't take over hosting of the site too soon, their own site has been down a few times lately.
Oh, and now Dotmusic will be one of the few websites on the Interent that can legally operate in the USA where, thanks to their overly broad patent lawas, BT owns exclusive rights to use web hyperlinks.
All those music sites in the USA are "stealing" from BT by using BT's "intellectual property" to link from one page to another without paying BT. No, I am not making this up.