Your word processor has spelling and grammar checkers. Your math word processor should check your math. (Not just arithmetic, but algebra, calculus, and proofs as well.)
That is what Lurch will do; it is a simple math word processor with a general-purpose math checker built in. Development began in June 2008 and will continue at least through August 2010, but usable (though simple) versions will be released as early and often as possible.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.