Yikes. Much of this discussion has been terribly misinformed. People have commented on what things work and what do not, but no one seems to have understood that there are too many intersecting issues to make a broad statement about particular players being gapless.
Here's the real deal: MP3s were never designed for gapless playback. This is because an MP3 file's length must always be a multiple of a certain fixed chunk of time. If the song's length isn't miraculously some multiple of that time, the file will be padded with zeros and there will be a period of silence at the end of the song... the mathematical remainder, if you will. Each song will randomly have a different amount of gap at the end.
At some point, a meta tag option was introduced into the LAME MP3 encoder, so a compatible player could later know the exact song length, and not play the padded silence. This means that both the MP3 file and the player need to be gapless-ready, or it's not going to happen.
So, to say any one player can definitively play MP3s gaplessly is not valid, since it also depends on how any particular MP3 was encoded. Also, some MP3s will luckily have such a small amount of padding, you might think that the player is somehow gapless, but won't be with most other songs.