An Australian figure of speech, which means to delve into the detail, or to discuss the implementation of something, rather than the high level abstractions. For example:

Businessman: Our Web site should be easy to use and easy to update.

Tech: Let's get down to tin tacks: so you want a web site with a PHP/MySQL backend with some kind of content management system?

Y'know, if you log in, you can write something here, or contact authors directly on the site. Create a New User if you don't already have an account.