Aw...now that's too EASY!!!! I was expecting to go into Acrobat V9, select this, crop that, paste this, center that, erase this and on and on.....you sure there isn't a more complicated way???? ;-)
Does it matter if the "original" PDF was created with Publisher?? I'm getting a black box in an empty space when I Save As a PDF from PS after I split the page. Everything else looks good.
seems that your 11x17 is text pdf, not image. (photoshop work on images.) try the following: create a blank 8.5x11 page (file > create pdf > from blank page). on the 11x17 use the touchup object tool; select and copy/paste the portion(s) that you want to have on one 8.5x11. do same with the portion that you want to transfer to the second 8.5x11. if this doesnt work, send me an email. i'll provide my e-address where you can send me the 11x17.
You don't say what flavor of Acrobat you're using, but in Pro there's an internal way:
menu - Document - Crop Pages Set left margin to 8.5, select "All" in the page range, click OK. Menu - File - Save As, and make a copy of those pages Menu - Edit - Undo menu - Document - Crop Pages Set right margin to 8.5, save the other half
This creates what you want visually (it'll print as a single page, etc.) but the cropped content is still in the files. If you want to ensure you've redacted the hidden objects from each half:
Menu - Document - Examine Document Untick the stuff you want to keep (metadata etc) but keep the hidden text and cropped content ticked, and click Remove.
http://www.acrobatusers.com/forums/aucbb/viewtopic.php?id=21418