This release includes lots of improvements including :

- a simpler way for writing macros
- support for nested functions
- generic methods overloading works
- support for CLR 3.5 extension methods (moreover boo extension methods)
- compile-time conditionals through ConditionalAttribute and the new -define SYMBOL booc option
- AttributeUsageAttribute is now supported and enforced
- a better interactive interpreter (previously known as booish2)
- warnings about unused private members, unused namespaces, unreachable code
- new error messages, including suggestions for misspelled members or types
- exception filters, exception fault handlers
- for loop IDisposeable.Dispose integration

Contributors to this release :
Avishay Lavie, Bill Pierce, Cédric Vivier, Daniel Grunwald, Marcus Griep, and last but not least Rodrigo B. De Oliveira.

Specter is back. It is a behavior-driven development framework for the CLI, powered by Boo meta-programming capabilities.
This release makes it work with recent Boo releases and introduces new features including standalone spec runners and a new 'subject' macro.

Full changelog and links here.

There is a nice post from Ayende Rahien about why he loves Boo on his blog.