The Sony Reader is not designed to run on the mac, but there is a simple workaround.
###[October 30, 2009] Update: The Sony Library has finally been released for Mac. So the text below might not be relevant anymore###
It is possible to download DRM-protected EPUB and Adobe Digital Editions formatted books to a mac and then transfer it to Sony Reader via usb.
Just once, one must go through the following process.
The two pieces of software, Sony Library and Adobe Digital Editions, must be installed on a Windows PC computer. Connect the Reader to the PC. From within Adobe Digital Editions, authorize the reader.
Now install Adobe Digital Editions on the Mac. Buy an EPUB or Digital Editions book from, say, www.booksonboard.com. The book can now be read on the mac through the Adobe Digital Editions software, while the file itself is found in Documents/Digital Editions/.
Connect the Sony Reader to the mac. Drag and drop the .epub or .pdf file from the mac folder to the Sony Reader. Done.
Do I think that Amazon, Sony and the book publishers are doing a good job of making it as painless as possible to buy and read ebooks? No. Please give us one open standard for ebooks, get rid of digital rights management and make all books available to everybody all the time through a new revenue model. 60 years from now, I do not want to discover that my precious ebooks are lost, since the rights management server has perished and no current technology can read the proprietary format.