Well that was the answer I needed. I went to 3 different shops (Futureshop, Indigo, and Source) and was told that I could highlight PDFs of my own. Reaffirming my belief that store flunkies know nothing about the products they sell.
Like a few others here, I am a grad student who scans chapters, texts, and/or downloads journal articles in PDF...and rather than printing them all out which wastes paper and requires me to have files and files of material, I had this CRAZY idea that I could put them all on an eReader. But if I cannot highlight passages, or even flag the page (or even better make a little note) then it's not much use. Most of what I need isn't even available in eBook format, and requires me to scan.
As for highlighting the PDF and then putting on the reader, it sort of defeats the purpose of the reader. If I wanted to sit in front of my computer for hours and read my PDFs I'd just do that. The hope was to be mobile (and portable)
Anyone tried the PDF to ePub converters (like you can download for free off Cnet)?