I'm not sure if an applicant's selection of track has a critical effect on the admission process, but I would suspect that it does hold some weight. I think this probably is more significant when looking at computational tracks vs the others (systems, cell mol, behavioral etc.) as computational likely attracts the most non-traditional candidates and would have slightly different expectations in terms of prior preparation. So my reasoning for inquiring into the tracks of those who had heard back from schools was to see if decisions were being sent out as a singular group (and those of us who haven't heard back should get comfortable with the idea that we had not been selected) or that some tracks operate more or less independently and correspondingly had not sent out their interview decisions yet. I imagine that this varies significantly institution to institution but I would not be surprised if this were the case, especially for places like Princeton which have a dedicated quantitative track or places like Berekley which have the semi-autonomous redwood center for theoretical neuroscience.