This looks promising! This functionality (and also the other projects on type-inference, etc linked in the research section) is very much needed. I'll use it myself, to be sure - but better IDE-related Ruby code analysis will be a great help in easing the complaints of the "religion of static typing" folks.
Wow. I'd love to see Textmate support this!
As a friend of mine put it: "OMG! Code completion!!!" =)