I read about it in EQ magazine. I'm an avid magazine reader and haven't seen ads for this service in any other type of magazine. Internet searches for keyword "weedshare" bring very few results, mostly to the Weedshare website. I have to wonder about whether or not it will be a big success if it's only advertised to other musicians.
Being the type of person who believes it is better to have your music on a site rather than not, I checked it out anyway. I must say the process turned me off a bit. I emailed asking about joining and uploading and they told me to "download their software" and "check it out" and if I liked what I saw, they'd "match me to an independent content producer." Sounded a little car-salesman-like to me.
No offense to car salesmen here, but if I ask a question, I like to get an answer, not a sales pitch. Also, I don't like the idea of "downloading software" to listen to a damned MP3! Maybe they are on-the-level, but the requirement to "download software" makes me skeptical. I might still do it, but I haven't gotten around to it yet.