Something in the back of my mind is scratching me and telling me there might be problems with using flock over NFS (I assume you're using NFS if all these workstations are writing to the same file?)

Another potential approach? how about saving files as:

localtime().hostname.extension?

That way, you can sort the files date/time order simply by doing an ls -l.

Note - this would assume that all the machines are synchronized to the same clock.