Just to chime in for those who might worry because their committee letters are generally sent out on the later side of the timeline, there are stellar applicants who forego the committee letter for various reasons (@
Narmerguy) but most people who qualify for one don't -- and probably shouldn't without good reason -- and do fine as well. Mine came in late August and from conversations with other applicants from my school, the earliest letters seem to have been sent out in early/mid August. As most of my friends can tell you, I was definitely not happy about this "delay" since my secondaries had been submitted by mid/late July and this was the last component to a complete application pretty much everywhere.
However, since then, I've gained a bit of perspective. @
LizzyM has mentioned that some prestigious school(s?) in the south also does(do?) this, and from the few threads that cropped up last summer, it seems this isn't *too* uncommon of a practice among a number of schools to put one at a severe disadvantage. Some schools such as UMichigan will even consider your application without even a secondary let alone your letters, and while these schools are few and far between, interview invites
will come, just not necessarily during the very first wave of invitations.
I guess what I'm trying to say is, if you have a committee that doesn't get their letters out until August/September, don't freak out just yet. As long as you complete the rest of your application (MCAT, primaries and secondaries) before your letter arrives, you won't be so far behind as to be at a disadvantage. From my understanding, committee letters generally do a great job bringing a cohesive narrative to your academic career and individual recommendations and are worth the wait. I guess this call to remain calm also applies to non-letter-waiting applicants as well to some degree: mid/late August is certainly not too late, so don't think you definitely must have everything done by the second week of July. Of course, if possible, earlier is better, but don't rush your secondaries. They do in fact matter and can make a difference.
In any case, best of luck to this year's applicants gearing up for their cycles!