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AFAIK, there's no framework, and there will be as many plugin development styles as there are shades of white in north pole.

I'd say WordPress Coding Standards are a blueprint for a good style.

You'll find lots of good examples and excellent coders here in WPSE. A nice starting point: http://wordpress.stackexchange.com/questions/tagged/plugin-development?sort=votes&pagesize=50

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Nowadays, I use Plugin Class Demo from @toscho as base for many plugins.

Right now, @Pippin is doing a series Introduction to WordPress Plugin Development 101 that may be of interest.