Billboard today announced an update to its Hot 100 list, a ranking of the top 100 songs in the US, adding weekly streamed and on-demand music data from AOL Music and Yahoo! Music.

The Billboard Hot 100¬†ranks songs by aggregating sales and radio data. Digital delivery began playing an important role in the chart’s composition in February 2005, when Billboard factored in the sale of digital tracks, as measured by Nielsen SoundScan from a comprehensive panel of online merchants. The chart also factors radio impressions and retail single sales, tracked by Nielsen SoundScan to reflect the 100 most popular songs.

The new formula is heavily weighted towards traditional radio and digital sales:

• Radio audience will average about 55% of the chart’s total points;
• Digital sales will account for about 40%;
• Streaming media will determine 5%;
• Physical singles–in line with the music industry’s retreat from that product over the past decade — account for less than 1% of the chart’s new formula.

While the updates are much needed, Billboard’s charts miss podcasts and other Internet media that are increasingly popular. For tracking “music 2.0” consumption, Apple’s iTunes podcast and music download rankings may offer more useful information than anything Billboard provides.