That's what I thought at first also, but the PopUp field only contains some information--in my case, the info related to how the popup appears (font, etc), but does not contain the attributes. I have tested the result of all three "Share" options in ArcGIS Explorer, with two different results, neither of which contain the full set of attributes.
If the attributes were all there and condensed into one string, I could export them to a table and parse, but they aren't all there.