Hulu and Boxee have a long, colorfulhistorytogether. For a while it worked, then it stopped working, then it started working again. So they were compatible. Sort of. Whether it will work again in the future is a topic of pure speculation at this point (Though I certainly hope it will).
This thread from 2009 says that at least one user had a better streaming experience on Hulu than on U-Verse online. Read the thread for further details.
According to this article, U-Verse Online offers "online streaming of television content and movies through content distribution partnerships with Hulu and some movie studios" (emphasis mine).
Digging around, I found a movie category called "U-Verse Movies" which appears to contain some exclusive content, some of it pay-per-view, some of it free for anyone, and other content that appears to be available for U-Verse subscribers only.
So I can't tell yet how extensive it is, but there appears to be some content here that isn't straight from Hulu.
Best Answer
Hulu and Boxee have a long, colorful history together. For a while it worked, then it stopped working, then it started working again. So they were compatible. Sort of. Whether it will work again in the future is a topic of pure speculation at this point (Though I certainly hope it will).