I received my RPi 3 today and tried it out using the same hardware setup that I've previously used for the RPi 2 and Zero, eg HP w1907s monitor (resolution 1440x900) with an HDMI to VGA adaptor, a wired mouse and a wired keyboard. The red LED illuminated, but there was zero activity from the other LED.
I downloaded NOOBS 1.8 and tried again; exactly the same, however I did establish that NOOBS started up when the SD Card was inserted into the Pi 2. I then tried to boot with the RPi 3 connected to the HDMI port on my new iiyama Prolite X2380HS (resolution 1920 x 1080) with the same other peripherals and it works.
I'm assuming that the graphics chip in the RPi 3 is different to the earlier models, but is there a way to get it to boot into Raspbi Config at least?