There are not many changes since 0.99.1 but a bunch of memory leaks were fixed including a pretty nasty one (https://bugs.freedesktop.org/show_bug.cgi?id=82659).
I have encountered the memory leak on several occasions on my laptop, leading to an unusable system (only killing/restarting upower helps). Please make upower-0.99.2 stable, 0.99.1 is terrible. On my system, I have updated now.
arm stable
amd64 stable
ppc stable
ppc64 stable
x86 stable
sparc stable
ia64 stable
alpha stable. Closing.