Yes, like the previous posts, it is called "Office Developers Edition" or "Toolkit" depending on which version of Office/Access your using.
It is a separate application that you have to purchase separetly from Office or Access, that when installed is a complete array of additional developer tools that are for someone that develops in Office or Access profesionally.
One of those additional tools include a Packaging program that creates a Distribution package (that you can customize) for the selected project, that allows you to install and run an Access mdb/mde/adp project/database on a computer that does not have a fully licensed copy of Access, with a setup.exe file and cabs that contain libraries, activex controls, custom files (help, ini, etc...) and the Access Runtime program that when you run the setup program will install all neccissary files in the appropriate locations. It is very similar to the create distribution process in VS where you add the VB Runtime to a package, only here you add the Access Runtime.
Other included tools that are very helpful is the program that aids in writing Help files, spytools, and the peice de resistence, an MSDN developers subscription. There are more tools but I don't use all of them.
Basically the Access Runtime Program that is installed is freely distributable and really is nothing more that an Access Viewer like the Word or Excel Viewers. You cannot edit or modify objects in the MDB/MDE/ADP files only open forms, reports, queries as they were last compiled to view and edit data as you normally would in a fully licensed version of Access.
I work with it everyday, and for me the bigest advantage is to compile an MDE and distribute it in with the appropiate version of Runtime as a compiled MDE will not run on any version other than the version it was compiled in. Because the company I work for, not everyone has the same version of Access and upgrading users to 2000 from 97 is slow, so distributing the 2000 Runtime the MDE will always work eventhough their fully licensed version is 97. And I don't have to worry about someone opening it in the wrong version and (accidently) converting it or having to support multiple version of the same project.