Welcome to WebmasterWorld Guest from 184.108.40.206
For type in traffic this may become a concern until/unless .biz catches on as much as .com. But as long as someone is clicking on your link (SE's, links etc...)then it doesnt matter at all. One plus may prove to be that .biz is only for bussiness use whereas .com's have been used for many purposes. Only time will tell.
Also, if the .com owners of your domain have some name recognition, you may actually get some of their traffic if you are more expert than they @ SE placement and linking.