I'm not sure if OCaml is becoming more or less popular, but I find the evidence for a decline less than convincing.  It is true that there is less traffic on this list, but it's hard to know how to interpret this.  I haven't gotten the sense that Python is in decline, but traffic on comp.lang.python has also been declining since 2005.

Google Trends is also a confusing metric.  For example, it suggests that Java, Python and C++ have been declining for years:

My suspicion is that Google Trends gives numbers normalized to the overall search world, and so things that aren't growing fast look smaller as search volume in general grows.  Obviously an up-and-coming language like clojure still shows an upswing, as one would expect from an up-and-coming language.

I thought this was a silly metric when it spiked up, and continue to think it's a silly metric today.  There are a tiny number of legitimate ocaml jobs (and the same is true for Haskell, Clojure, Scala, SML, etc.) and the ups-and-down in this tiny sample are not statistically significant.  Again: don't pick OCaml because of the large number of OCaml jobs out there.  There are very very few, both now and in '05.

Reliable metrics on a community like this are hard to come by, but things seem quite vibrant to me.  There are always new OCaml startups popping into existence, new libraries being written, and new things coming out of INRIA (for example, the arrival of modules as first-class values, which is expected in OCaml 3.12).  From my point of view, there is still no platform out there I would rather be using.

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