I would say that, in general, these statements carry little weight and you should not put much stock in them. That said, as with your communications with the program, the more specific the feedback, the more weight it likely carries.
If a PD writes me a highly personalized e-mail with details of my app and our interview together, I can safely assume that (1) I will be ranked by the program, (2) I will probably not be ranked in the bottom third, and (3) that the PD has taken time of out his busy schedule to contact me. Of course, none of this means I am ranked to match or even ranked very highly, even if the PD says I am.
Likewise, if the PD tells an applicant "We'd love to have you here," it's highly unlikely the applicant had a poor interview performance. The applicant can also probably safely assume #1 and 2 above. Since this is the most one can safely assume even if told point blank they are ranked to match, then it does hold some objective significance. This is especially true given that some programs told me they only rank half or at most 3/4 of interviewees.