I went to SUNY Stony Brook 20 years ago. There and everywhere else on Long Island they were called "Heros" Never heard of a wedge until I got into the Road Food thing 15 years ago.
Then it's me being prematurely senile.
There was certainly no shortage of Westchesterites in Kelly E at the time so it's possible we used the term among ourselves and translated to Long Island-ese when we ordered out. A quick survey of LI Pizzeria menus on line failed to turn up the term "wedge" for sandwiches so that adds weight to the faulty memory theory.
I did a Google search on "meatball wedge" today to see if the term's extent has spread or shrunk since the last time I looked into it a couple of years ago. I only went about 10 pages in so this research is by no means comprehensive.
Overall, use of the term "wedge" seems to be limited primarily to Westchester, Putnam and Dutchess Counties upstate as well as the Bronx and Manhattan. A web page welcoming The Onion's staff relocating to Manhattan mentions the term: http://www.disobey.com/ghostsites/netslaves/comments/980260490.shtml
There appears to be limited use in Orange County, NY, too -- I wonder if that has anything to do with that area's continuing influx of downstate natives. This tentative finding doesn't seem too far off from the consensus reached by the illustrious readership of fark.com (they seem to think it's a Westchester-only term, but Farkers seem to be generally younger and therefore possibly not be as worldly as we cosmopolitan Roadfooders
Some interesting findings (well, if you're into that sort of thing, anyway):
1) There's a place in State College, PA (The Gingerbread Man) that sells something they call "wedges," but they're sandwich fillings baked in a shell ala calzones/strombolis as opposed a hero-style sandwich. That's a first encounter with that use of the term for me -- I wonder what the story is there: http://gmanstatecollege.com/menu/wedges.asp
2) One of my local places, Vazzy's in Stratford CT, sells "wedges" but not the far-more-typical-for-this-area "grinders." Very unusual and unexpected. Also Manero's in Greenwich, Vinny's in Stamford and a couple of places in Norwalk sell "wedges" but they're on the other side of Bridgeport and therefore spiritually closer to NY.
3) When I was growing up in Northern Westchester, the term wasn't limited to hot sandwiches and that appears to still be the case there: (http://www.ginoscarousel.com/lunch.htm
); however, my quick survey seems to indicate the use of the term "wedge" outside the NY area is limited to Italian deli-style hot subs, (e.g., chicken parm, meatballs, sausage & peppers, etc.) and mostly used by places portraying themselves as "NY-Style" pizza joints. For example:
4) School Menus -- a lot of them are on line and seem to be a good source for regional food terms. I only two school menus using the term "wedge" west of the Hudson (Highland Falls, Wallkill) and nothing further north than Dutchess County. This may be a bad time of the year to be looking for school menu references, though, as schools are on summer recess. Also the fact that a "wedge" tends to be a big sandwich might mean it's less likely to show up on menus for kids. Lots of schools all over the country list a "Pizza Wedge" on their menu but it appears to be another term for what New Yorkers refer to as a "slice."
5) The term may be falling out of favor in the city -- I didn't see as many NYC references as I recall a few years ago when I last looked into this. Perhaps this has something to do with the continuing influx of non-Italians and non-Greeks into the NY Pizza business (Albanians come to mind as the biggest newer ethnic group getting into NY Pizza these days but there may be others.)