Same place it always has been but the HD/Users/<yourname>/Library is hidden in OS 10.7 and 10.8. The path should be HD/Users/<yourname>/Library/Application Support/Adobe/Adobe Illustrator CSX/en_US/New Document Profiles
Since you're nearby, do you have any idea why each time I try to save a default page, after changing the typeface from Myriad Pro, why the default returns to Myriad?
Ignore the last one. I figured it out. It makes no sense why Adobe makes it such a crooked line to these results when their other programs work much more easily.