While this is not exactly what I was hoping for it is a step in the right direction. I have always wanted to have a Zen like theme on my Bold with the current weather conditions along with the next 5 days. Until now I have been making due with BBWeather which is free but is a bit finicky when it comes to updating the homescreen icon.
Ari from Volcari Software let me know that HomeWeather performs a bit of what I am looking for but is sadly only available for the Storm. HomeWeather will change the background of your Storm to display the current weather represented by an image. It has some serious functionality restrictions like being unable to show temperature values and only working in the US but it is getting closer.
You can configure the forecast period to include the current weather or today/tomorrow. It is pretty pricey at $9.99 ($8.99 on sale until August 31st) but it has a definite coolness factor.
Now if only RIM would let developers show a website as your BlackBerry background… That would really open up a world of possibilities.