The news first broke on the Sonic Stadium forum, and out of curiosity I went to have a look...and it's actually true. Everything from the original site that you'd access from a Dreamcast browser or the Sonic Adventure disc is there - all of the guides to the VMU mini games, Chao gardens, level maps...even the community sections and competition winner listings.
Link: Sonic Adventure Homepage
Update: I managed to speak to the creator of the site, a cool guy called Scott. He replied to my email asking for further info on his reasons behind the Sonic Adventure homepage resurrection:
"I run a Chao website, Chao Island. I've always been a big fan of Sonic and Sega, especially the Dreamcast. I still update my Chao website to this day and we have around 10k members registered after multiple forum closures!
I'm always looking for ways to keep the Dreamcast spirit alive and restoring this classic site gave me the chance to do that.
My website has no ads, and I make no profit from it, I just try to do my best to keep a happy community and get as much Chao information out there as possible!"
- Scott, Chao Island
Thanks to Scott for answering my questions, and be sure to visit Chao Island for all your Chao needs!