...because they included a newer gcc version (4.3.1 rc1). Typical make error: "expected ‘;’ before ‘<’ token". This is a known bug (see this discussion), and there is a patch - there are just some include statements missing.
Download the patch file mpm-2.7.3107-gcc-4.3.patch and run
patch -p0 < mpm-2.7.3107-gcc-4.3.patch
in the directory where you untarred the sources.
If your patch fails, try patching manually (read the patch file), it's just one or two lines each in less than 10 files. Mpm should compile OK now (HowTo).
A nice diff and patch intro can be found at linuxforums.org.
Considering the easy fix, I suppose they'll dispose of this bug soon ;-)