ChaCha says it now has more than 1 million users and has answered more than 27 million queries since it launched its potentially addictive mobile answering service in January.

Combined with its quarterly growth rate in the second quarter, ChaCha said that makes it the fastest growing mobile search service, surpassing both Google and Yahoo! in both WAP and text-based search growth rates. That’s according to the latest data from Nielsen Mobile, ChaCha said.

ChaCha increased its market share in the U.S. mobile search market to 7 percent, tying for second place with Yahoo! at the end of June 2008. ChaCha also ended the quarter with an 800% growth rate compared with Yahoo’s 200% growth rate.

ChaCha uses a base of more than 35,000 “guides” who answer customer queries 24/7. Users text a question to 242 242 or call 1-800-224-2242 from almost any mobile device, and a guide usually returns an answer within minutes. Questions range from what’s the weather like in other cities to the age of Bob Dylan.

Recently, ChaCha also launched its mobile marketing solution, ChaCha 1:1, and it is partnering with premium brands including Coca Cola, Fifth Third Bank and McDonald’s to implement relevant mobile marketing campaigns.

Other companies offer ask-and-answer mobile services, but Indianapolis-based ChaCha has been grabbing headlines as of late. On Monday, it accepted the 2008 North American Frost & Sullivan Award for Product Innovation. In April, ChaCha won the grand prize in the mobile software Fast Pitch developer contest sponsored by AT&T.