I believe it means it is still in the experimental stage, and the programmes are still being tested mate, but someone else may be able to help with a better explanation.
A mathematical measure of the sensitivity of rates of return on a portfolio or a given stock compared with rates of return on the market as a whole. A high degree of such sensitivity indicates moderate or high price volatility.
God2, that may be the economic definition, I'm not sure. In this case, roundtoit was correct. It means, as it does in all programming, that it is in a "testing" phase. Typically, there are two testing phases, Alpha, which is testing to see if the program even loads up and performs just basic functionality. This phase is easier to test and is usually done by the programmers/developers themselves. The beta phase, like the Live Chess portion of this site is in, is where more, in depth, testing is done. Most bugs don't show themselves right away, but only come out after significant use of a program. So, developers get other people, ideally ones who aren't involved with development of the program, to run it and use it, and see what they can break. Then they go in and fix the bugs. Live Chess does have bugs, and it will break from time to time. If/when it does, it should be reported to the site's dev team, so they can fix it and work toward a better site for all.
Beta; what does beta mean in the context of live chess?