I made a patch to talk so it would display timestamps.
The following instructions apply to a debian system, it should be fairly similar in any other system:
1. get the patch file from here: http://www.falamaki.id.au/~sara/projects/talk/talk-timestamp.patch
2. download the source for netkit-nettalk:
apt-get source talkd
3. go to the directory where netkit-ntalk-0.17 is, and apply the patch:
patch -p0 < talk-timestamp.patch
4. download the dependencies for making it, if you don't already have them:
apt-get install libc6-dev apt-get install libncurses5-dev apt-get install libwrap0
5. run:
./configure make
6. copy the talk binary somewhere useful, e.g.:
cp netkit-ntalk-0.17/talk ~/bin/talktime
7. run the new talk binary instead of the old one, in the above case, use talktime instead of talk. You don't need to change talkd at all, just the talk client. You should see it display something like this:
[22:05:49] [22:05:50] hello world [22:05:52] now we know what time the previous message was sent! ------------------------------------------------------------------------------- [22:06:08] yay time!