I think I have *finally* pin-pointed the Weather 0.51` docklet bug in latest few RK Launcher builds. I have also figured out why the author of RK Launcher couldn't replicate the bug!
Basically, the Weather 0.51 docklet WILL NOT auto-update it's weather display if you set RK Launcher to Automatically hide! That's how I keep it all the time because I don't want it to constantly overlay anything on my desktop, but I know that many people keep it visible at all times. If you keep it visible, the weather auto updates fine, but if you set it to auto-hide, you have to update weather manually every time you want to see it.
I have confirmed this to be the case on my home computer, and the ofice computer. They both run Windows XP SP2. I hope raduking can fix this, especially because it used to work fine in an older build