I have two answers, actually. My iTunes Library contains close to 5,000 (I'm at work, so I don't remember the exact number at the moment).
The answer I voted corresponds to my 4 Gb nano's current count: 557, and that's with only four small photos. Some might say that I'm getting much less than the advertised "1,000 songs in your pocket", but the vast majority of my files are encoded at 192 kbit, and at least 30% of them are extended remixes.