Details of this weekend's update:
http://kentonsprojects.blogspot.com/2010/08/ekam-no-longer-restricted-to-building.html
If you want to try compiling some C++ with Ekam, here's what to do:
1) Make sure that your code is in a directory called "src".
2) Make sure that compile.ekam-rule (from the Ekam code) can also be found somewhere under "src", otherwise Ekam won't know how to build C++ code and thus will not do anything. (You can, of course, just plop the entire Ekam package in your source tree.)
3) Run ekam from the parent directory of "src". It will create a directory called "tmp" and put all output there.
For now you can only compile code that requires no libraries (other than libc). Indexing of installed libraries will come eventually.
Note that Ekam will not display any errors until it has run out of other things to do, as until then it optimistically hopes that it will find something that will fix said errors. I'm not yet sure if this is a significant problem, or how to solve it if so.