What looks sexier on your resume though: "Creator of backbone.js" (Not trying to pick on backbone since it's a great project, but you can read the entire source in an hour) or "Contributed to making AR 5% faster for certain queries"

I'd much rather see 10 people put their time towards making one project better, then seeing 10 people start 10 divergent projects with dreams of becoming the next DHH, but I recognize that there are other factors at play.