Update: Well, results have been published, and (Wow !) I'm one of the 2 winners of this challenge. What a great surprise ! A lot of good work have been done by the other finalists, too. You really have to view their submissions.

Now that the deadline is past, and the official answers have been published on the Network Forensics Puzzle Contest.
it's now time for me to publish my own submission.
For this one, i've written 2 tools in ruby.The first is named smtpdump and could be used to retrieve interresting informations on SMTP conversations in a pcap file. The second docxtract is able to extract files from a docx archive.

Well, this time, it seems the challenge will be hard...
Some of the contestants have already published their own solutions or tools, and all the solutions i've already read so far are really good ones !