September 11, 2015: The YubiKey Edge-n, that we launched in April 2015, will replace the YubiKey Nano on March 1, 2016. Designed in the same innovative small form factor, the YubiKey Edge-n includes all the features and benefits of the YubiKey Nano, with additional support for the emerging open standard FIDO U2F.
Update May, 2016: Our current small form factor is the YubiKey 4 Nano. This is our 4th generation YubiKey — providing stronger and faster crypto — that we launched in November (see our blog). If you still require the YubiKey Edge-n, contact Sales for large volume orders (500+).
For more information, see YubiKey 4 Nano.