Is there a way to have the pattern source live by itself, and then be referenced by different pattern libraries, or would this need to be separate themes (foundation_patterns, foundation_patterns_pl, foundation_patterns_fractal?) If separate themes, the pattern library specific themes could themselves have dependencies on foundation_patterns. The UI Patterns module's approach to this could have an impact here as well.
Pattern library is manually including the relevant pattern templates from the theme. Something like a discovery process would make this much nicer, but it works for now.
Is there a way to have the pattern source live by itself, and then be referenced by different pattern libraries, or would this need to be separate themes (foundation_patterns, foundation_patterns_pl, foundation_patterns_fractal?) If separate themes, the pattern library specific themes could themselves have dependencies on foundation_patterns. The UI Patterns module's approach to this could have an impact here as well.