ArborGen is seeking permission from the USDA to sell eucalyptus trees with genetically engineered cold tolerance (to allow plantations in the southern U.S.). The genetic engineering doesn't worry me, but I am a little wary of eucalyptus in general. They're somewhat invasive (and hated by the locals) in California, though I have no idea how competitive they are in the Southeast. They're also working on loblolly, one of the dominant native trees in this part of the continent. Either way, little work has been done to date to improve tree varieties (even by traditional breeding) for obvious logistical reasons. Once timber crops have been transformed into the twisted, dependent freaks that the rest of our domesticated plants and animals already are (by traditional breeding), ecological invasion will no threat at all.
At any rate, their improved varieties of loblolly pine should mature in 18 rather than 26 years, and their eucalyptus in 4 rather than 7! ArborGen's motto is "More Wood. Less Land." (which I love!), and if they can pull off these variety improvements they may be able to back it up. I would much rather consume wood and paper harvested from supercharged, intensively-managed (small!) plantations than from the massive clearcutting that's still dominant in the Pacific Northwest.
Remember, all the resources you consume have to come from somewhere - it's much better for the environment to split land between high-yield, high-tech ag and preserved wilderness, then the muddled, Pyrrhic "eco-agriculture" that tries to produce crops and preserve wilderness on the same land and fails to do either well.