At Waxy.org, Andy Baio has a couple of excellent posts about the Whitburn Project, an effort to catalog and preserve every pop song released since the advent of recording. Baio downloaded the project's spreadsheet, and performed some analyses of the data. Highlights of his findings:
1. A pop song's average length is becoming longer, hovering at around 4:00. (This strikes me as way too long. I generally head for the exits at 2:30.)
2. The pop charts turn over much more quickly in recent years. Prior to the mid 1990s, few songs came and went from the charts in four weeks. Since then it has happened with increasing frequency.
3. Nevertheless, fewer songs chart then in previous decades.
4. There have been more one-hit wonders in the '90s and '00s than in the '60s and '70s.
Also interesting, if not surprising: This tag cloud of the words in pop song titles reveals that two of the most frequently used words are "love" and "baby." I guess that makes the Supremes "Baby Love" the ultimate pop song.