Sure, iTunes can join tracks, but only if they're consecutive CD tracks, and you haven't imported them. This script allows you to join any two (or more) MP3 tracks (repeat: MP3 tracks only), provided that they are the same format and bitrate.
Also see Join Together, an application that will join any type of files.
Perhaps Also of Interest...
downloaded 6m 7s ago
Continuously update your desktop picture to current track's artwork
downloaded 7m 27s ago
Display the width x height of selected track's artwork
downloaded 10m 24s ago
Droplet adds files, creates playlists based on folder name(s)
downloaded 11m 27s ago
Remove iTunes tracks disassociated from files
downloaded 20m 9s ago
View/Edit tags of selected track(s) in single window
downloaded 23m 14s ago
Perform search-and-replace on text in your choice of tags