When we first started talking about LAMP, it stood for Linux, Apache, MySQL, PHP, Perl, Python... and other M and P projects, such as mod_perl, mod_python, PostgreSQL and so on. The letters were arranged horizontally, but many IT builders began talking about them vertically: as a "stack": Linux on the bottom, and a pile of other stuff on top.

So here's a simple question: how high (or wide) is that stack now? Put another way, how many open source projects sit on Linux today?

I just asked Ethan Zuckerman, who said the question was "interesting", and that one approach would be to subtract out the non-Linux projects from SourceForge. Right now there are 154,092 projects on SourceForge. I don't know how many run on Linux, though I'm sure it's a huge percentage. But SourceForge isn't the only place where open source development projects live.

You can go looking with directories such as Linux.org's, collections such as Freshmeat's or Tucows', or code search engines such as Google's, Koders' or Krugle's. But so far I haven't been able to find a number.

But that's just me. I'm sure one or more of the rest of ya'll have the answer. Or many answers. What are they?