Is there a freeware app to add comments to a PDF?

The Foxit Reader (http://www.foxitsoftware.com/pdf/reader_2/whatsnew23.htm) allows to add comments to PDF files.

I wasn't ready to submit my comment yet...

It is not free, but its' a lot cheaper than the full version of Acrobat.

So, now I'm done :)

Thanks, khkremer, but I really need to know if there's a free one.  

I am not aware of a free one.

Let's turn this around: What are you trying to do?

I need reviewers to be able to add comments to PDFs that are generated by a learning content management system.  The comments thus added can be re-imported into the learning content management system.  The comments must be added as PDF comments, but it isn't feasible for us to purchase licenses for all reviewers.

A freeware PDF editor would solve the problem, but I couldn't find one.  It looks like there isn't one.

Thanks, khkremer.  That's an interesting idea.  I'll check it out.

Thanks for your help with this.  The application developers let me know that only Acrobat Pro would ever work with their app.

Foxit reader is a charm!
I can successfully open a PDF generated with Acrobat 7 and add comments to it, then reopen the PDF with Acrobat Reader 7 and the notes display fine!
Saves me from having to "comment-enable" PDFs for others...they can do it themselves!
Thanks for sharing the solution :-)