UPDATE AT 11:51 A.M.: Heard from a source with knowledge of the situation that the Nationals have been limiting ticket purchases by groups with Pennsylvania area codes. They appear to be taking some steps to curtail a repeat of Opening Day. I'm sure there will still be a sizable Phillies presence, but probably not to the degree of what happened in April.
Four months after they took over Nationals Park on Opening Day, the Phillies fans appear to be on the return.
Phillies Nation, one of the fan sites that organized group trips to Washington for Opening Day, is planning a return to Nationals Park for next weekend's Phillies-Nationals series. A post on their web site said Phillies Nation is sold out of seats for next Saturday's game against the Nationals. I just saw this tonight, so I haven't gotten a chance to find out how many tickets the group has, but I'll see what I can dig up -- and if the Phillies groups also have seats for Sunday's game, where Stephen Strasburg is supposed to face the two-time NL champions for the first time.