I got it in my 3rd year. I think it was helpful. Never mentioned explicitly, but added to a strong research background. Also, since Einhorn is an OREF grand-champion, I credit the fellowship with my interview offer at BU (which I unfortunately had to decline).

Keep up the good work, and never ever rest on your laurels.

-Grizzle-

While I can't speak for the OREF grant specifically, I had received some grant funding myself and several places asked about the grants in the context of their general research questions - stuff like: did you write the application, how competetive, etc... so I think it would definitely help. You might want to work it into a sentence in your personal statement that it you were one of ten selected or whatever so that people realize that you didn't get some run-of-the mill summer training funding.
I think it is important to mention that many places have PhD's/full time researchers on their committees: they have a vote, they review your app, and they ask you interview questions. From my perspective on the interviewee side, it seemed that their ears definitely perked up with regards to these kind of things. Did their opinons make a big difference in rank lists? who knows... but I definitely felt that it gave me an advantage.