There are several websites (e.g. http://www.kombuchakamp.com/ and http://kombu.de/english.htm) as well as books (e.g. search Amazon for "Kombucha") about kombucha tea and most of them claim that drinking it has a positive effect on health. The main claim is that it improves your immune system and detoxifies the body. Further claims even go so far to say that it helps people which suffer from cancer or AIDS. This could be explained as well from the improved immune system.
Drinking Kombucha promotes better health by detoxifying and improving the efficiency of your digestive system which boosts immunity.
or see http://www.kombuchakamp.com/health-benefits-of-kombucha for a larger list of claimed health benefits.
However, there are also people which warn for kombucha, as it can lead to lead poisoning if done in an inappropriate container, or for other reasons.
Are there any scientific results supporting at least some claims of an improved health due to kombucha consumption? I'm looking for an answer showing research results in favor or against the main claims mentioned above. Results about similar claims are also welcome.