(URL removed)
yes, Sega is asking for who has a dreamcast, i don't know why but it's an idea that gathered many fans in just 1 day
by going to (URL REMOVED) you will need to put your dreamcast serial , a password and a email to send the aproval.
you will then receive after a while 2 emails, one with the serial and pass and another one with the aproval from the admin.
then your email will be (serial)@user.dreamcast.com
is sega preparing something? i don't know
edit: proven hoah/fake
Aww man i don't have a dreamcast...:'( So Kireek tell me what happen ok!

"Various news sources such as Kotaku and Sega Nerds have posted news that
http://www.dreamcast.com is asking Dreamcast owners if they still own their machine by registering their e-mail address and console serial number. The registration page is offline and "temporally" suspended, however there is a lot of evidence to prove that this site is in fact fake and not run by Sega.
This includes the source code of the site being poorly written, the server not being on Sega's dedicated servers, the e-mail verification coming from a non-Sega domain, Google Ads and Play-Asia advertising on the homepage, as well as a Sega Direct link, even though Sega Direct is due to close at the end of March."
Got this from Wikipedia. As much as I hope it's not a hoax, there is a lot of evidence to suggest it is. Either way, i'm still gonna sign up if the service comes back up, since I have 3 DC's I've got nothing to lose.

updated the 1st post, some ppl say it is a hoax, all those that were affected don't worry, in worst case you will receive viagra junk mails or something similar.
until then, don't register.
I'd also like to point out that dreamcast.com is not registered by sega.
i was a bit suprised with the site, i mean i like dreamcast and sega, so why didn't i knew the website, i never saw it before, yet it made me beleive it was new and since i had nothing to lose i took my oportunity.
I've looked into this, and after contacting sega i got this reply:
Hello,
Thanks for writing in with this -- SEGA is aware of the issue and is looking into it. This information on this site is not endorsed by SEGA in any way, and we strongly recommend that you not give any information to them. SEGA's legal department is looking into the matter.
-Edward
SEGA Support