Aubi7,
The oil prices are rising rapidly. Vegetable oils and Tallow prices are following the price of petroleum oils as they are an alternative fuel feedstock.
Jatropha does require manual harvesting, but it won't be long before someone develops a mechanical harvester for Jatropha. Plantations will probably need to be laid out to comply with the harvester requirements, but that can easily be done.
Many countries are lacking in trees which were harvested for firewood/lumber in the past. This will revegetate (albeit a monoculture) and possibly improve the climatic conditions surrounding the plantations.

I hope so.

Tony