The ID came with free webmail, as everything does these days. Yahoo!'s new webmail client is quite an impressive showcase for the power of their AJAX user interface library, and does some quite slick things. Unfortunately, Yahoo! being considerably more corporate than Google, the pane in which you see your emails is tiny, with the bulk of the space being given over to a large, animated banner ad. (This is in addition to context-sensitive text ads.) I think I'll stick with Gmail for the time being, thanks.
I just hope that Yahoo! don't decide to fold Flickr into their mainstream photo-sharing site or otherwise attempt to maximise their revenue by cluttering it with ads.
BTW, those using Uploadr.py on Linux (or similar systems) to post to Flickr may be interested in knowing that there's now a new version that plays nicely with Yahoo! authentication.