Mine strangely started working after I installed the "slide to dismiss" tweak from Cydia - one respring after installing and the status bar icons work as well as the app icon theming. I rebooted to confirm this isn't a one off - works fine now.
There must be an odd interoperability problem with other tweaks - I have intelliscreenx, zephyr, barrel, bitesms amongst a couple of others installed - but then the real question is why would it suddenly start working after just installing a new tweak if it was some other tweak stopping it from working correctly?
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libweather is one of the two components installed to your phone when you install the weathericon package in Cydia.
So I guess what andrewr23 meant was uninstall weathericon, reboot, then uninstall libweather, reboot, then reinstall the package and tweak about with the settings until it works.