I have it on good authority from several Adobe CS5 sources that Droplets are not supported in 64bit in Apple 10.5.x.
If you’ve created Droplets for, say, Adobe apps in CS4, they can be run in Apple 32bit x32 on 10.5 .
Droplets are supported in 64bit 10.6 .
Much of this is beyond my understanding but, “Droplets are not supported in x64 on 10.5 due to a deprecated API that Apple will not be fixing”
Also, “Well, people can A) thank Apple for their architectural changes and then B) pay Apple $30 for a Snow Leopard update. Heads they win, tails you lose.”