Is it possible to export pdf documents that allow the user to copy and paste the exported code/text?
The following table demonstrates what is pasted after copying the example symbols from a pdf exported from Mathematica.
If this isn't possible an explanation of why not(what about pdfs prevents this functionality) would be appreciated.
After reading Alexey's answer, it has become clear that the pdf editor that you use to copy the text makes a big difference.
When you copy text from the pdf reader Foxit or from Google Chrome's built in reader the clipboard stores the following.
If you copy the data from the pdf using Adobe Reader 11(W7 and M9) in addition you get a RTF format on the clipboard. The RTF format allows Mathematica to reconstruct the original data.