In remarks made during the company's semi-annual financial results briefing, Nintendo president Satoru Iwata said that developers and publishers will finally be able to have demos available on the Nintendo eShop. Along with that comes the ability to offer what Nintendo's calling "add-on content". Demos can be locked to a certain number of trials, meaning that you probably won't be able to play a sample forever. And accessing those trial versions will get a little easier with the addition of sleep mode downloads.
Lastly, the House of Mario is prepping the eShop to be reachable via the web, specifically through PC and smartphone. But, you won't be able to purchase software via web interface initially and will instead be taken to a product page in the 3DS web browser after taking a picture of a QR code. Full purchase functionality is planned for the future. These moves might be the first steps in closing the gap between the 3DS and smartphones, making it more of a connected device and less of an isolated, one-way client. At the very least, these changes show that Nintendo's listening to feedback and trying to implement it.
Semi-Annual Financial Results Briefing [Nintendo]