"The statute of Jeune Enterprise Innovante (JEI), created in the 2004 budget bill, applies to small to medium businesses (in the EU, that means <250 employees, <50mil turnover, <40mil assets). The businesses must be less than 8 years old with R&D representing at least 15% of their expenses."
The benefits seem ridiculous. The article says they include exemption from revenue tax, payroll tax and an exemption from capital gains tax for associates (investors? not sure if I read that bit right).
Seems like the Wikipedia article might be a bit out of date, though. A French government website had a different list of benefits not including anything about capital gains, but adding an exemption for property tax.
Someone native should probably check my understanding, but it looks like you get a pretty sweet deal if you can convince the French government you're doing R&D.