Wifi Webclient + analog voltage monitor hardware suggestions?

I am looking to put together a 2.4Ghz capable analog voltage monitor capable of reporting its readings back to a webserver.

I have enough expirience coding php and C++ to be confident in that regard, but could do with some input on the hardware capabilities and compatibilities.

Basic requirements of the system:

Connect to a 2.4GHz access point with a hidden, but know SSID
Internal or external antenna is fine
Staticlyor dynamically assign an IP
Support for WPA / WPA2 desirable
Measure a 12v input voltage (through a voltage divider if required)
Periodically transmit the reading to a server, most likely by simply embedding it into the URL loaded and using a GET on the server
It would be nice to be able to utilise the board as a Webserver if I decide to use it for other projects.

There appear to be a number of 3rd party boards and shields that would do what I want, but I've no idea if it will be harder on some than others, or to what level they are supported.

An Arduino Uno with an async labs WiShield 2.0 or just the async labs BlackWidow 1.0 would appear to be up to the task, but async labs seems to be winding down? How capable are the currently avaliable devices and what sort of support / libraries are avalaible for them?

Is there any cheaper / better / more supported / easier hardware for my project?