In addition, the firmware update will add the ability for publishers to release demos, "for which they can put a limit on the number of trials." Also nice (and previously missing): the ability for users to download content while in sleep mode.
Iwata revealed future plans for a web-based PC/smartphone interface for the eShop, in order to make it easier to discover highly rated games without first having to check the eShop on the 3DS. At first, the web eShop will generate QR codes that you can point the 3DS at to buy stuff. "That function is already included in the upcoming system update for the Nintendo 3DS," Iwata said. Nintendo plans to add full web-based shopping later.
The next step, and the one about which Nintendo didn't say much: actually putting some things in the eShop to buy.