if you're talking about changing the batteries the easy way, via a premade solution in Cydia, I haven't been able to get them to work either. None of the little tweaks appear to be working, at least not via Winterboard. I've tried signal meters, wifi meters, batteries...none of it works. It'll download OK from Cydia and will show up in Winterboard and let you check it and drag it wherever you want in the theme hierarchy, but it won't actually apply any changes.