In particular, note this clause from yelp's agreement:
"5. Restrictions
You agree that you will not, and will not encourage, assist, or enable others to:
A. display, perform, or distribute any of the Data, or use the Data to update or create Your own business listing information;
B. Use the data in any manner or for any purpose that may violate any law or regulation, or any right of any person including, but not limited to, intellectual property rights, rights of privacy and/or rights of personality, or which otherwise may be harmful (in Yelp's sole discretion) to Yelp, its providers, its suppliers, end users of this website, or Your end users;"
http://33bits.org/2010/03/15/open-letter-to-netflix/
In particular, note this clause from yelp's agreement:
"5. Restrictions
You agree that you will not, and will not encourage, assist, or enable others to:
A. display, perform, or distribute any of the Data, or use the Data to update or create Your own business listing information;
B. Use the data in any manner or for any purpose that may violate any law or regulation, or any right of any person including, but not limited to, intellectual property rights, rights of privacy and/or rights of personality, or which otherwise may be harmful (in Yelp's sole discretion) to Yelp, its providers, its suppliers, end users of this website, or Your end users;"
http://www.yelp.com/html/pdf/Dataset_Agreement.pdf
That said, reading the dataset agreement, I'm not sure I'd care to participate even if I could.
edited for formatting