Welcome to the forums,
The hosted demo is currently 5.0.6_GA_2244.RHEL4_64 still. (Type $set:get version in the main search bar of the AJAX web-client.)
Bug 29903 - iPhone 2.0 Zimbra <-> ActiveSync Push Mail Does Not Put Phone into Standby Mode, Consuming Battery Quickly is marked fixed in 5.0.9 which was
just released yesterday.