Version 3.1.1 is now available. This fixes a bug that causes failure on recent Perl versions.
What it is: TeXcount is a Perl script for counting words in LaTeX documents. It parses valid LaTeX documents counting words, headers, formulae (mathematics) and floats/begin-end groups.
TeXcount is included in the CTAN TeX/LaTeX archive, and thus included in several TeX distributions. If you have TeX installed, chances are you may already have TeXcount.
How to stay updated: If you wish to be kept updated on changes and latest features, you can subscribe to the TeXcount RSS news feed.
Questions and Answers: There is a Frequently Asked Questions page which may already answer your question. Alternatively, you can post your question on the StackExchange TeX questions board with the texcount tag which I will normally follow, or email me directly.