As of JetPack 2.2.1 there is now a local development/debug mode.
http://jetpack.me/2013/03/28/jetpack-dev-mode-release/
use:
define ('JETPACK_DEV_DEBUG', true);
in your wp-config and you should have access to any modules that don’t require a connection to function.
Update, since around v3.3 another local development trigger was added via filter instead of define.
Latest is now here: http://jetpack.me/support/development-mode/
Development mode automatically gets enabled if you don’t have a period
in your site’s hostname, i.e. localhost. If you use a different URL,
such as mycooltestsite.local or something, then you will need to
define the JETPACK_DEV_DEBUG constant.You can also enable Jetpack’s development mode through a plugin, thanks to the jetpack_development_mode filter:
add_filter( 'jetpack_development_mode', '__return_true' );
As of Jetpack v3.9 there is also now a staging mode filter that forces a site to be recongized as a staging site rather than production: https://developer.jetpack.com/hooks/jetpack_is_staging_site/
add_filter( 'jetpack_is_staging_site', '__return_true' );