We spread the good new like any techno centered family - email's, shutterfly photo slideshow, texts messages, myspace, facebook and a few phone calls. We started out by calling everyone but after telling that very involved story 10 times over, I just didn't want to be on the phone anymore! It wasn't just a quick "We're engaged!" call - it was a 15 story and then the congrats. So then we moved on to the wonderful world of the web. It worked great. I sent everyone to the slideshow I posted about. I posted it everywhere and got lots of responses. Granted, most were a quick congrats followed by praise for all Adam's planning and creativity.
I realize that it's not the traditional way, and Emily Post would probably have glared at me, but I think it worked great for us.
And - bonus! - my Dad used iphoto to make our slideshow into a photobook! So we have that to show anyone we encounter in person and we have it to keep forever! And my parents have a copy of their own, and they sent one to the Future-in-laws too!