It's not just the &'s in the Event Names. It is anywhere in iPhoto. Even if it is hiddin in the meta data. You can determine if you have this in one of two ways:
1) If you click on your iPhoto Library and select Show Package Contents you will see the details of what is in it. Open the AlbumData.xml file using a text editor. Do a search for &. If you find them then it means you still have them somewhere in the iPhoto library. Look for some key words before the & such as Album or something to help you figure out where they might be. OR....
2) In iPhoto click on Photos on the upper left to pull up all of your photos. Then do a Find for the &. What might happen is you get a list of photos that come up but when you look at them you may or may not see the &, such as in the name of the photo. Change any/all that you can see. If you are still getting a list of photos and you can't see the & anywhere then chances are you have the problem that I had, which is there is old info tied to the photo that you cannot see. For example, the actual photo file name. Try dragging those photos that look like they do not have an & associated with them onto your desktop. My guess is they will now have a file name with the & in them. For all of them, drag them out. Change the file name on the desktop. Delete the originals in iPhoto and then drag them back in. Also check your Album names. If you have Albums with the & rename them.
Now, if you are still having problem it could be that the Album has meta data, such as a default song, tied to it that the latest iPhoto will not show you. The only way I could find to fix this was to create a new album, copy the photos into it and then delete the old Album. Close iPhoto and iTunes. Delete your iPod Photo Cache folder in your iPhoto Library package contents.You should be all set.
Again, the problem is the & but it is in both visible names such as Albums, Events and Photos, as well as hidden meta data carried over from older versions of iPhoto.
FYI - I am still having an odd error where iTunes lists a ton of bizarre events with Date Names as the Event that do not exist in iPhoto. But at this point I don't care since I can finally sync everything. I am going to call AppleCare to see if they have any ideas on how to get rid of these Events appearing in iTunes photo lists but not in iPhoto.