The documentation on the website is from the 0.9.1 release and may be incorrect in some details. The mailing list since 2008 and this FAQ should supersede anything in the documentation.
Elephant does not work properly under the default clbuild configuration due to it's UFFI (not available through clbuild) dependency. We have made attempts to port Berkeley DB to CFFI (available through clbuild) but without success; there are subtle issues that lead to obscure bugs and the original FFI developer who wrote that code left the project in 2003 or 2004 and no one else has yet had the time and expertise to resolve them. The workaround (thanks to Sebastian Tennant) is:
The most common active configurations of the 1.0 release branch is on SBCL/Linux/Postmodern+BDB and ClozureCL/MacOS/BDB. Elephant is known to work on these platforms when properly configured.
A patched version of Berkeley DB 4.7 is recommended (see below).
If you are running a 64-bit lisp, Berkeley DB will need to be built accordingly. Package managers (e.g., MacPorts or Debian's APT) tend to build/ship 32-bit versions of Berkeley DB, in which case building a 64-bit version from source is the appropriate solution: