According to Jimmy Wales blog, Wikia Search has shut on March 31, 2009. Wikia had raised funds from well known personalities and it was being promoted as ‘open source search’. It did not take off 🙁
The alpha version was released in Jan 2008. According to an article on cnet, Wikia was getting merely 10,000 unique visitors a month for the past six months. Sounds very low 🙁
I personally believe it is difficult (rather impossible) for anyone to take on Google Search. Having said that I must mention we are seeing a lot more referals from Yahoo and Live.com over the past 2 months.