Atlanta food writer and blogger Jennifer Zyman purchased her first Apple iPhone the day it went on sale last year — “I waited in line; I’m a geek,” she admits — then upgraded to the sleeker, faster 3G model as soon as it hit stores this summer. She is as keen on her phone as she is on discovering the newest Midtown restaurant. Now the two go together. Among the 10 “apps” or applications she has downloaded for her phone are two restaurant locators — Yelp and Urbanspoon — that use the phone’s global positioning software to find nearby restaurants and even provide customer reviews.