* immutable models via `config.allow_mutation = False`, associated cleanup and performance improvement [44](https://github.com/pydantic/pydantic/pull/44)
* immutable helper methods `construct()` and `copy()` [53](https://github.com/pydantic/pydantic/pull/53)
* allow pickling of models [53](https://github.com/pydantic/pydantic/pull/53)
* `setattr` is removed as `__setattr__` is now intelligent [44](https://github.com/pydantic/pydantic/pull/44)
* `raise_exception` removed, Models now always raise exceptions [44](https://github.com/pydantic/pydantic/pull/44)
* instance method validators removed
* django-restful-framework benchmarks added [47](https://github.com/pydantic/pydantic/pull/47)
* fix inheritance bug [49](https://github.com/pydantic/pydantic/pull/49)
* make str type stricter so list, dict etc are not coerced to strings. [52](https://github.com/pydantic/pydantic/pull/52)
* add `StrictStr` which only always strings as input [52](https://github.com/pydantic/pydantic/pull/52)