Dartmouth received a record 17,768 applications for the Class of 2013, according to Dean of Admissions and Financial Aid Maria Laskaris, bucking a trend of stagnant or decreasing application numbers among similarly sized, private liberal arts colleges. The College intends to accept 1,800 applicants during the regular decision process, for a total class size of 2,200, Laskaris said, resulting in an overall acceptance rate of 11 to 12 percent, the lowest in Dartmouth’s history.
Ivies use "likely" letters for recruited athletes in place of the NCAA Div.1 letters of intent.
Dartmouth issues 2 types of likely letters; one set for recruited athletes and the other set (the bulk of the 500 given during RD) are for students that the college is highly interested in enrolling (some come with an invitation to Dimensions). The likely letters go out in waves starting in february.
I'd guess for a deferred applicant to get a LL, something significant would have had to happen since the deferral. Dartmouth, like other schools, uses LL's to try to get under the skin of it's top applicants, kids it knows will also be accepted at HYPS. That's pretty much the same thing they do in the ED pool with unhooked applicants, accept those they don't want to risk losing to competitors.