Good news for people who follow E3, Nintendo plans on streaming their E3 Media Presentation live on their own servers, on a service they call the Nintendo Network. Being an official source, hopefully it means it'd have the most stable servers for the broadcast. Time for the broadcast is 9 AM PST/12 PM EST on June 7.
Also on the site, they tease that any other major Nintendo-related E3 announcements will be announced on the site as well, so keep it in your bookmarks.
http://e3.nintendo.com/