At Elimnators request I have added optional attributes to Unit Particles. start-time and end-time will synchronize the particles with the units skill animation. For example smoke particles can 'puff' smoke in this manner:
<skill>
<type value="stop" />
<name value="ss_skill"/>
<ep-cost value="0" />
<speed value="300" />
<anim-speed value="100" />
<animation path="models/power_plant_idle.g3d" />
<particles value="true" start-time="0.5" end-time="0.7">
<particle-file path="smoke_particles.xml"/>
</particles>
<sound enabled="false" />
</skill>
Notice the: <particles value="true" start-time="0.5" end-time="0.7">
This will start particles when the models animation is at 50% and end particles at 70% (and keep cycling along with the animation). This change is in svn.