The whitepaper at http://msdn.microsoft.com/en-us/library/windows/hardware/gg4... indicates that Windows timer coalescing requires an application to explicitly opt in. The article describes OS X Mavericks' support as applying to all upcoming timers while on battery power (presumably excluding particular classes of timing-sensitive applications, such as audio playback), which would be a much more aggressive approach than in Windows.
Yea that's fair. I was actually thinking of timer coalescing on the server OS for improved power efficiency/performance -- I'm sure IIS, MSSQL, etc. all opt-in to coalescing responsibly.
It sounds like the OSX version is more of a "forced timer coalescing" feature.