The only software that reads Adobe ADEPT PDFs is Adobe Digital Editions. This is already on the Sony Readers and is due to be added to many EInk Readers this summer. It is not available on any multi-purpose handheld devices, but Stanza has announced their intention to add ADE to their iPhone app (I don't know if it will read PDFs though).
If you want to use a more full-featured PDF reader, or shift the ebook to a more widely available format, see
Adobe ADEPT DRM for PDF circumvented.