<http://www.mikematas.com/blog/2005/01/how-to-make-life-poster.html>
This guy is also one of the Delicious Library guys! Shoebox only do up to 12x18, but I notice nextbyte do a service here in Oz now too (not directly through iPhoto though - you still have to export and email/burn to cd) with Digital DaVinci: <http://www.digitaldavinci.com.au/> Mainly books, but I'm sure they would do a photo of that size if you ask. Anybody of any locals offering this kind of service yet? Seeya Rod!
