As presented in the journal Zootaxa, Xixianykus was an alvarezsaurid. This was a bizarre group of feathered dinosaurs with ostrich-like bodies and stubby arms tipped with huge claws. Its skeleton was not as well-preserved as that of Linheraptor, but enough of it was recovered to recognize it as a new kind of alvarezaurid. More than that, the authors of the new paper identified Xixianykus as a parvicursorine, or a specialized subset of alvarezaurids which may have relied on ants and termites for food. While the legs of these dinosaurs were well-adapted to running, their short and stout front limbs would have been used to rip open insect nests, and the authors of the paper propose that Xixianykus may have been like modern-day anteaters, moving between different nests every day to get enough food without wiping out the colonies it depended on. Further skeletal remains will be required to confirm this hypothesis, but based upon what the close relatives of Xixianykus were like, it is reasonable to assume that it shared the same traits related to a diet of ants and termites.
For more on this discovery, see Dave Hone's post at Archosaur Musings.
XING XU, DE-YOU WANG, CORWIN SULLIVAN, DAVID W. E. HONE, FENG-LU HAN,, & RONG-HAO YAN, & FU-MING DU (2010). A basal parvicursorine (Theropoda: Alvarezsauridae) from the Upper Cretaceous of China Zootaxa, 2413, 1-19