Here's a post from a few weeks back at Creativebits that generated a nice discussion of the use of Adobe Illustrator (a vector graphics program) vs. Adobe InDesign (a page layout program) for doing ads and other creatives. Photoshop is thrown into the mix as well. In Switching from Illustrator to InDesign the author is looking for arguments to use to convince a bunch of studio artists to not use Illustrator and Photoshop for everything and instead use InDesign for laying out press layouts. Lots of valid points are raised. Depending on the type of project, Illustrator is not necessarily a bad choice.