Deltik.org is now Deltik.net, and every web resource should be redirecting to the new domain.
.org was originally intended as a top-level domain for organizations that didn't fit under other categories, and Deltik was supposed to be such an organization. Today, .org is often registered by non-profits and open-source projects. Although Deltik is still primarily focused on open-source contributions, it's not much of an "organization" anymore, as it's run by just me.
The deciding factor for the move was a nice sale on .net domains that I found by chance. I registered 10 years of deltik.net for $69.78, which I believe is quite a bargain!
I intend to keep deltik.org around indefinitely, though, since I've had it for over 13 years now, and there will continue to be backlinks outside my control pointing to the old domain.
The previous time Deltik changed its domain name was on 11 July 2008, when the community raised enough money to buy deltik.org. At the time, Deltik had no financial backing, so it took advantage of free hosting services for its early years.