New features have arrived at downloads.mozdev.org (D.MD.o). I'll just enumerate them to save space:

You can check your closest mirror (and list of other
available mirrors) by visiting the following link:
<http://mirrors.mozdev.org/ip-check.html>. You will be redirected to
your closest mirror automatically; no need to select it from the
list when you download a file.

<p>

1. Providing downloads for recently uploaded files directly from D.MD.o (bug#17900)

   This makes it much easier for project owners to distribute test packages and get critical updates out to their users.

   For regular file releses we ask that you post your download file several hours (at least 4 hours) before you announce your new file or post an updated updates.rdf file. This will ensure that your new file has a chance to be distributed to as many mirrors as possible.

   3. Additional download statistics - mirrors.mozdev.org has been updated with new stats that show the number of downloads from our mirrors in the past 30 days by mirror and by region.