Well, this thread certainly was active while I've been away. My thanks to everyone who helped with Zetren's questions.
1.3a2 should arrive in March. 1.3 final will arrive around Bungie Day if all goes well, with at least one beta release prior. Lately my day job has been my day-and-most-nights-and-some-weekends job, so I'm way behind schedule and might fall further behind, but I have the most important part done: Aleph One is running on SDL 2.
Zetren: thanks for the reports. Aleph One does not use the registry, so I'm not sure what's going on with #1, but I'm glad you were able to get 1.2.1 working again. SDL 2 brings a lot of bug fixes, so hopefully the AA and vsync issues will get better soon. If not I have other ideas for improving compatibility, although they may have to wait for 1.4. Unfortunately Intel graphics usually don't have great OpenGL drivers, so I can't promise anything, but not having vsync is incredibly annoying.
Erika: at this point, it's better to wait for 1.3a2. I'll start a new thread when that's ready, and throw this one to the wolves. 1.2.1 is still the best "daily driver" for most people. 1.3a2 will start fixing bugs and limitations in 1.2.1, replacing them with entirely new bugs. The beta will come once I've fixed everything I know I broke, and need help to find more stuff broken since 1.2.1.
3371-Alpha: regarding the starscape, have you tried copying the plugin from 1.3a1 into 1.2.1? It should work fine, but I haven't had time to test it. If it works, I'll put it on Simplici7y as a standalone download.