It does not mean much me saying so, but the SLF4J and logback projects are gaining traction. The project mailing lists are showing real signs of life and community interest, whereas the download statistics are showing significant upward trend.
We are not at the same levels of popularity as commons-logging or log4j. Nevertheless, it is very encouraging to see users responding favorably to our work. It feels like the early days of log4j, and that's pretty damn exciting.