I just found this campaign on kickstarter and found it very interesting: basically it's a Atmel SAMD21 (cortex M0+) combined with a ESP8266EX WiFi-module, realized on a very small form-factor (1,05inch x 0,73inch) [26,5 x 18,5 mm] https://www.kickstarter.com/projects/krom/wino-board-the-tiny-10-arduino-with-wifi
it's somehow Arduino Zero compatible, though it uses a smaller processor of the same family SAMD21E17 (128kB Flash / 16kB RAM / 48 MHz) (it's meant to be programmed with the arduino ide 1.6.5+) http://www.wino-board.com/index.php/en/wino-board/technical
I think the advantages are obvious: - really very small - it's cheap - Arduino software compatible - Arduino hardware compatible (with additional programming board) - integrated Wifi & antenna
some disadvantages are: - no integrated USB port (need a small add-on board for that) - no 0.1" [2.54mm] breadboard-friendly header (it's 2.0mm instead)
what do you think of it ?
(I'm not related/associated in any way with the campaign owner...)