Windows Mobile (5 or newer)
smartWatchM.cab v1.2.6.0 (20100227)
smartWatchM-st.cab v1.2.5.1 (20091213) - use in case of heavy battery drain (HTC Advantage, Universal), MS BT stack only
smartWatchMToday.cab v0.1.0 (20090315)

Windows (XP or newer)
OpenWatch v0.1.0.4 (32 bit/64 bit) (20100110)

Android (2.0 or newer)
OpenWatch for Android v0.5.0 (20100128)

BlackBerry (4.5 or newer)
OpenWatch for BlackBerry v0.1.7.3 (20100127)

J2ME
OpenWatch DEMO v0.1.0 (20090819)
Rockola BT v1.1.0 (20090819)

PalmOS (5.0 or newer)
OpenWatch for PalmOS v0.1 (20091219)

Linux
OpenWatch.py v0.1 (20091220)
OpenWatch.py v0.1 (20091220) - no media keys

Maemo (5)
OpenWatch v0.4.0 (20100221)

Symbian (S60 3rd FP2 or newer)
WIP

Bada
-

Mac OS
-

iPhone
Currently not possible (try asking Steve)

webOS
Currently not possible

Windows Phone 7
Currently not possible