I've written about entrepeneurship and taxes previously. There is some pertinent new research in this area.
Dylan Matthews over at Wonkblog has a nice summary of a new NBER working paper about taxes, entrepreneurship, and growth--marginal personal income tax rates and corporate tax rates are only found to be significant deterrents to growth when they are exceedingly high (once they get too high, high-ability entrepreneurs exit their paths to entrepreneurship).
My colleagues Yasuyuki Motoyama and Kate Maxwell have a new paper out that Kate mentioned yesterday that I think provides a very clear analysis of how small businessses interpret and respond to questions concerning taxes and business friendliness (hint: rate levels don't matter as much as (i) the presence of any tax whatsoever and (ii) the complexity of the tax code).
It is still unclear to me how exactly tax rates affect incentives for investors who have to decide between young firms and large, established firms.