We've posted carpool/rideshare lists for NPS 2011 on the official Facebook page. You can see the listings here:http://www.facebook.com/event.php?eid=155008287906868
That page will take you to sub-sections such as "from points NORTH," "rides from the AIRPORT," etc. I decided to go with Facebook instead of these esteemed forums (a change from previous years) because these forums tend to be for PSI members and insiders, while the Facebook page casts a wider net. For stuff such as carpools, we're looking to reach as many people as possible.
Don't let the price of gas keep you from cheering on your team at Nationals. Get a road buddy and get to Boston!