AnthraX and the other kernels by its developers still thwart the GPL license of their Linux kernel by requiring users to sign-up to download the kernel after being "authorized" to download the file. By not widely releasing the AnthraX kernels to the public but trying to make itself a "private organization" and "internally" distributing the compiled kernel binaries via the project web-site, they go without releasing the kernel source-code while claiming GPL compliance -- if they technically aren't distributing the compiled kernel.
The issue has been brought up in months prior at GPL-Violations.org but to no avail. The lead AnthraX developer doesn't want to give out his kernel's source code reportedly over concern of other developers taking credit for his improvements and work on the kernel. There's also been claims that the kernels incorporate code that's under NDA from vendors.
Eric Appleman, an open-source developer long crusading against the project, pointed out in a new kernel mailing list thread this week about the AnthraX developers still proceeding without providing the source-code to this "private" kernel. There's also links in that mailing list thread to some of the recent Google+ posts, for those interested in some light reading this holiday week.