Q: When I download a zip from github, what is the hex string at the end of the file name represent? If I go to https://github.com/wesm/pandas and click the "Download" button to download a zip (or tar) archive of the repository, the file name of the archive I get is:
wesm-pandas-0.3.0-93-g1d40e65.zip

I can see that wesm-pandas represents the project name, and 0.3.0 represents the project version.
Does 93 represent the number of commits on that branch?
What does g1d40e65 represent?

A: See https://github.com/blog/651-annotated-downloads for details on the filename format: the 1d40e65 represents an SHA of the last commit on that branch, and the 93 is the number of commits since the latest tag.

A: After the username and the project, the filename is obtained from the output of:
git describe --always

Example from the man page:

[torvalds@g5 git]$ git describe parent
v1.0.4-14-g2414721
i.e. the current head of my "parent"
  branch is based on v1.0.4, but since
  it has a few commits on top of that,
  describe has added the number of
  additional commits ("14") and an
  abbreviated object name for the commit
  itself ("2414721") at the end.

http://www.kernel.org/pub/software/scm/git/docs/git-describe.html
So in your case, 93 is the number of commits since 0.3.0 and the hex after g is the sha1 of the latest commit
