Voting by mobile phone

An article titled "Estonia to vote by mobile phone in 2011" caught my attention. First off, I had never heard of a country called Estonia, and then I found out that it would be the first country to allow voting my mobile phone. Mobile phone voting would be allowed for the next parliamentary elections in 2011. Last year, they used internet voting, and they claim it was secure and there was no fraud. I am not currently aware of any other country who has done that.

For the mobile phone voting, voters would be required to obtain a free authorized chip for their phones, which would verify the voters identity. They say that system has already been tested and has been proven secure and reliable. I wonder what measures were taken for the internet voting they had previously done and which would be more secure?

From a little bit of research on Wikipedia, I found that Estonia has a population of 1.4 million which is about 1/200th the population of the United States. It is a very small country, which is probably why it is easier to implement these changes.