Headed to my first training sessio with Sunderland...cold and rainy— Steward Ceus (@StewC_AllDay) November 26, 2012
Currently second on the depth chart behind Matt Pickens at goalkeeper, Ceus has worked his way up since being drafted in 2007 and got his first-ever starts in MLS in the final two games of the 2012 season. Getting time training with a big club like Sunderland certainly can't hurt his chances at eventually usurping Pickens for the starting spot.
Sunderland are currently sitting at 16th in the EPL table.
Though he is participating in training with the Black Cats, it does not mean that he will be getting loaned or sold to the EPL side. Similar moves are made with MLS players all the time, and Rapids players in particular have trained with Arsenal quite a bit in recent years due to the link between the two teams. As the Rapids' backup keeper, he's likely not anywhere close enough to get a spot on Sunderland even if he was sold to them, anyway.