I did a few searches on the web for some cosplay events on the East Coast and came up with these:

http://www.katsucon.com/

Katsucon is held in Washington D.C. in February at the Omni Shoreham Hotel which is located at 2500 Calvert St NW, Washington, DC 20008.  Looks like you'll have to wait until next year for that one 

http://www.setsucon.com/

Setsucon is held at Day's Inn in State College, PA from January 26th to the 27th.  Looks like I'm doing so hot at finding any that you might be able to attend in '08. 

Comic-Con will be held in Baltimore on September 27th and 28th.  Honestly, I'm not 100% sure that people dress up to attend, but I think that they do.  You can check out more info directly here:

http://www.comicon.com/baltimore/index.htm

Here are some more great pics of latex and pvc Cosplay attendants:

There are some very creative people within the Cosplay scene.  For those of you who are not familiar with what it is - cosplay is a word that stands for 'costume play'.  It originated in Japan with people who were really into video games and fantasy anime.

These people would create costumes like their favorite characters and then dress up and go to designated meeting places where they could talk and admire each others work.  I have seen some excellent costumes and ensembles that Cosplers have put together from both latex and pvc fabric.

Unfortunately, blogs aren't really the place to showcase tons of images, but I will show a few of my most recent favorites.  BTW - growing up I was a huge fan of GI Joe, so the COBRA outfit is especially dear to me :)

More to come on North American Cosplay and how you can get more info.