Here's a walkthrough of WeatherTalk in action:
A pretty interface, with location look-up and all weather data from Foreca. The 'Today' tile animates to also show the 'Now' weather. The green dots indicate (I presume) lack of rain?
Tapping to log into Facebook brings up the usual password and authorisation screens, along with (right) this slightly disconcerting error - ignore it and log in proceeds as expected!
Back in Settings, your 60 day login authorisation is confirmed, along with imperial/metric units choice and the option to run WeatherTalk without the earth photo in the background... (right) tapping on the share icon besides a day later in the week gives the ability to share this forecast data point with your Facebook friends.
And on Facebook (here viewed in Gravity), here are my two test posts. Note that the graphic shared is the correct one for the day you selected to share; (right) once logged in, the interface is complete - the look ahead forecast is for five days - the four shown scroll up to reveal the fifth.
You can download WeatherTalk Qt for free here in the Nokia Store. It's a nice little utility, though Twitter and (now) Google+ sharing would be nicer to have, from my point of view.