Eddie,
yes, one can always join tracks....but this is not a good solution as the tracks have no ability to then be individually selected. While this might be fine for the tracks in a classical performance, it doesn't work well for popular song tracks where many folks want to be able to mix their music up like a radio station.
yes, the joined tracks should have less performance impact on the nano than on the hard drive iPods...but again joining is not a general solution I imagine for the large majority of iPod listeners.
what many of us want from Apple is a more sophisiticated buffering scheme that enables gapless playback for all songs, even when the songs are not joined....this is a feature of other digital players, but seemingly requires more effort or compute power than Apple is willing to invest. When people speak about a "gapless playback" feature on these forums, it is this capability (or a similar crossfade capability that iTunes provides) that is being discussed most of the time, and that's what I thought you were referring to.
Tom