Here are programming language trends from very different sources.
1. According to TIOBE Programming Community Index, here are the top 10 programming languages.
|Delta in Position||Programming Language||Ratings
TIOBE Programming Community index page, shows the trends of increasing/decreasing popularity as well and contains lots of other useful information. This changes every month so please make sure to check the latest.
2. This programming language usage index shows information about languages used in open source projects. It has a slightly different story to tell. Obviously VB is not the most popular for open source software.
3. The SkillMarket provides a tech hiring patterns.
5. In addition you can check indeed.com to check the job trends of the top languages. Here are both absolute and relative trends for Aug 2009
Probably tracking the searches at major book sellers, publishers may provide more useful information as well.