"Beta" is programmer's jargon for a piece of software that isn't quite ready yet. They think it works, and they want people to use it to find out, but they won't guarantee that it's really ready for prime time.
A piece of software has usually 2 major stages of development, Alpha (Also known as F&F - Friends and Family , where the software is tested by those who make it and their close ones and its under NDA " Non-Disclosure Agreement"). The next major stage its the Beta. The software its ready to be released to a small community so it can be tested intensely so bugs and stuff like that can be found and fixed before the Release Date is reached.
TheDarkStar Raj.K and I have written a massive coding and setup article on the wiki. Please click the link at the top of this page and go to the setup area to get the source.