This update adds the eShop (i.e. the place to buy Mega Man Legends 3 Prototype Version) and an Internet browser to the handheld. Aside from Mega Man Legends 3 Prototype Version, Nintendo has not confirmed any other titles for the eShop’s launch.
Nintendo of Japan announced a similar timeframe, June 7th, but Japan’s clock is ahead of ours, so the firmware update could be simultaneous. Nintendo’s E3 press conference will follow in the morning at 9AM on June 7th.