Theists and specifically, the 6,000 year Creationist love the point out tha so called flaws with Carbon 14 because it has a very short half life. What they fail to point out is that Geologists already know this and don`t use C14 to date things older than about 50,000 years old. They use the same principles used with C14 with other elements.
Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old. However, the principle of carbon-14 dating applies to other isotopes as well. Potassium-40 is another radioactive element naturally found in your body and has a half-life of 1.3 billion years. Other useful radioisotopes for radioactive dating include Uranium -235 (half-life = 704 million years), Uranium -238 (half-life = 4.5 billion years), Thorium-232 (half-life = 14 billion years) and Rubidium-87 (half-life = 49 billion years).
The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy. However, radioisotope dating may not work so well in the future. Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.
The theists are being completely misleading with these claims from "scientists" about the folly of radio carbon dating by conveniently omitting the fact that dating is also done with other elements with far greater half lives.
And for those of you that don't believe in radiocarbon dating, perhaps you'd be interested to know that it calibrates perfectly to the Dendrochronological clock (that stretches back some 11,000 years)...