The Garden Professors' blog
For example, here are some recent topics:
Restoration ecologists - you need us!, which analyzes the lack of advice on good planting techniques for the ecologists.
Propagating in the air, which covers the latest methods for air-layering to increase the success of stem cuttings on hard-to-root species.
Cornmeal myth busted, which refutes the effectiveness of cornmeal as a pesticide.
I don't know about you, but I'd much rather garden with scientifically proven methods than old gardeners' tales, so I follow this interesting blog.