As of June 22, 2011 a statement left on http://kradminer.com indicates that due to denial of service attacks and other mischief krad miner will be shutting down. The author goes on to state that he wrote the software in about 5 days and had intended to open source the software. However no one he spoke to was willing to purchase the software rights for the price of 50btc, the reasoning for not opening the codebase is vague and uncertain.
"So unless a better offer comes along I have no intention to release this specific code, since it will likely just be used for pathetic rip off sites." - quote from krad miner
On Sept 4th, 2011 someone posted a query to the the bitcoin stackexchange wondering what happened to Krad Miner.
On June 3rd, 2012 user temujin9 answered that he had purchased the code from Krad for 50 btc in order to open source it. Temujin9 has renamed Krad Miner as Tumen Miner and published the source code on his github account.