No,.. a "little" Radiation is NOT good for YOU!

Government scientists and media shills are now “reexamining” old studies that show that radioactive substances like plutonium cause cancer and arguing that exposure to low doses of radiation is good for us (a theory called “hormesis”).

It is not just bubbleheads like Ann Coulter and pro-nuclear hacks like Lawrence Solomon are saying it as well. In virtually every discussion on the risk of nuclear radiation, someone post comments arguing that a little radiation makes us healthier.
However, the official position is that there is insufficient data to support the hormesis theory: As Wikipedia notes:

Consensus reports by the United States National Research Council and the National Council on Radiation Protection and Measurements and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) have upheld that insufficient human data on radiation hormesis exists to supplant the Linear no-threshold model (LNT). Therefore, the LNT continues to be the model generally used by regulatory agencies for human radiation exposure.
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The notion of radiation hormesis has been rejected by the National Research Council’s (part of the National Academy of Sciences) 16 year long study on the Biological Effects of Ionizing Radiation. “The scientific research base shows that there is no threshold of exposure below which low levels of ionizing radiation can be demonstrated to be harmless or beneficial.

See this, this, this and this.
Most proponents of the hormesis theory claim that data from the residents of Nagasaki and Hiroshima shows that residents exposed to low levels of radiation (i.e. some miles from the bomb blasts) lived longer than residents who lived so far away that they were not exposed to any radiation.
However, as Reuters noted in 2000:

Japanese survivors of the atomic bomb have their life expectancy reduced by an average about 4 months, which does not support claims that survivors exposed to low levels of radiation live longer than comparable unexposed individuals.
To clarify the question of whether atomic bomb survivors have enhanced or reduced life expectancy, Drs. John B. Cologne and Dale L. Preston from the Radiation Effects Research Foundation, Hiroshima, Japan, studied 120,321 survivors and estimated their radiation exposure and mortality rates after 45 years of follow up.
They report in the July 22nd issue of The Lancet that median life expectancy fell by about 1.3 years per Gy of estimated radiation dose, and declined faster at higher doses. At doses below 1 Gy, median life expectancy fell by about 2 months, while exposures of greater than 1 Gy resulted in a median loss of life of 2.6 years.
Drs. Cologne and Preston estimate that at a dose of 1 Gy, 60% of those exposed died from solid cancer, 30% from illnesses other than cancer, and 10% from leukemia.
“These results are important in light of the recent finding that radiation significantly increases mortality rates for causes other than cancer,” they write.

A large study of bone cancer in survivors of Nagasaki and Hiroshima published in March of this year also showed no hormesis, but rather increased cancer risk even at low doses. (See this and this for more evidence that low levels of radiation can cause cancer.)
Other data has also been misinterpreted by those who advocate that a little radiation is good for you. For example, the above-quoted Wikipedia article notes:

In popular treatments of radiation hormesis, a study of the inhabitants of apartment buildings in Taiwan has received prominent attention. The building materials had been accidentally contaminated with Cobalt-60 but the study found cancer mortality rates more than 20 times lower than in the population as a whole. However, this study compared the relatively young irradiated population with the much older general population of Taiwan, which is a major flaw. A subsequent study by Hwang et al. (2006) found a significant exposure-dependent increase in cancer in the irradiated population, particularly leukemia in men and thyroid cancer in women, though this trend is only detected amongst those who were first exposed before the age of 30. This study also found that rate of total cancer cases was lower than expected.
(used with permission:Washington Blog http://www.washingtonsblog.com/ source material & links available at my site crossposted via: Nakedcapitalism ) pic from wikipedia and Im outta breath...must be hormesis (chuckles)