There appears to be a v8 beta available at
http://www.eudora.com/download/eudora/mac/8.0/Eudora-8.0.0b3.en-US.mac.dmg
I haven't tried it yet.

Update to kelter's update:

[from http://www.eudora.com/faq/]

October 11, 2006

QUALCOMM is announcing that its Eudora email program will become an open source product effective the first half of calendar year 2007. As an open source product, it will be free to all customers.

I would have to disagree with footstep. While the user interface certainly looks more like an OS 9 application, the features of Eudora have stayed current. Let's not forget that Eudora 5 and Eudora 6 were both released in the Mac OS X era.

Yes, it'll be great when QUALCOMM finishes Eudora 7, and we get a more modern version of Eudora. But to say that Mail outclasses it...that's not my experience. I've tried to switch to Mail more than once, and found it woefully inadequate, compared to Eudora. Not as pretty, but I'll take functional over pretty, every time, at least for email clients.

UPDATE: Eudora Mac beta 6.2.4 is out. Eudora has said they are working on version 7 to be OSX Tiger ready (read as: using WebKit, Spotlight etc.) Check it: http://www.eudora.com/betas/Looking_for_Mac_Eudora_7.html

The current Mac incarnation of Eudora is a little sad: a carbon program now a full generation behind Eudora 7 for Windows. It's changed little since the days of OS 9. This may be comforting to some users, but Eudora's performance and feature set is hopelessly outclassed by OS X's Mail and free alternatives like Thunderbird.