This is the simple way to get Boost into your iPhone code.
I've been porting a large C++ project to the iPhone. It uses the excellent Boost libraries. Building Boost for the iPhone is not impossible, just a bit of a pain in the arse.
There are a number of good examples of how to do this online, for example the Backstage blog entry here and Matt Galloway's blog here. They are useful hints that help you work past the impenetrable Boost Build documentation.
However, the story does not end here. Those instructions allow you to build a set of libraries for the simulator, or for the iPhone OS. But not both. This means that your Xcode project setup gets fiddly with different link paths for the different targets.
You can solve this by creating a "universal" fat library. The lipo tool can be used to shunt the individual libraries together. Not tricky, just another step.
Now, for bonus points it would be sweet to construct a "Framework" for the Boost libraries, allowing you to use them in Xcode like any other iPhone framework. I've already blogged on how to do this here.
Of course, if you were sensible, you'd wrap this up in a script so that anyone can use it. A script a bit like this one.
I've set up a Gitorious project for this script. Feel free to use it.