Depends on the project. For simple command line tools, I usually start around 0.9[.0] since I only consider releasing or packing them when they're near completion (or ready for beta testing, anyway.) More complicated projects start around 0.1[.0] and some never even see 1.0. I consider 1.0 a release version (or at least a locally tested beta or release candidate) and plan accordingly.
With team projects, whoever puts the first version tag gets to decide :).
