The two teams have much in common. The Pirates have had 19 straight losing seasons, the Orioles 14, and yet both teams have gotten surprisingly good results so far. The Pirates are currently 32-27 and are tied with the Reds atop the NL Central; the Orioles are 34-26 and are one game out in the AL East.
In both fanbases, there's a sense that things could come crashing down at any time, and that's a feeling for which Pirates fans have ample justification, having watched their team contend in 2011 until the end of July, only to fall apart completely as they came down the stretch.
I explore these themes with Orioles fans in the new Camden Cast podcast over at Camden Chat, SB Nation's Orioles blog. If that's not enough for you, the Bucs Dugout Podcast did a show with a similar Pirates/Orioles team a few weeks back.