ESP8266 already got a lot of attention, but the problem is that this chip has more to offer than just UART to WIFI module, there is C compiler, SDK which allow you to write user program and have access to all GPIOs and resources of the chip so instead to add dumb microcontroller to ESP8266 module you will be able to put all your application in the ESP8266 itself.
The problem is that most existing modules do not allow access to all ESP8266 resources… until now, you see the untilate development board for ESP8266 now, it have access to all ESP8266 resources, GPIOs, bootloader etc.
The module MOD-WIFI-8266-DEV have UEXT connector footprint on the back so it can connect to all OLIMEX boards which have UEXT connectors, two rows of 0.1″ connectors for breadboarding and split pads which could be soldered directly to PCB.
For these who want to use ESP8266 just as SERIAL-to-WIFI bridge MOD-WIFI-ESP8266 is the better choice with smaller size and soldered female UEXT connector it direcly will plug to any board with UEXT.
MOD-WIFI-ESP8266-EVB with Relay, button, Power supply, GPIOs access is in production and will be available in couple of weeks! It have on it MOD-WIFI-ESP8266-DEV on socket.