Most of Linn's changes and enhancements to rtems have been incorporated back into the main  rtems tree. For example, rtems' virtex bsp is largely based on code from Linn. As such, you're probably better getting the source from the rtems site which will include both our changes as well as many others made by the rtems community.

However, there are a few changes that either weren't appropriate for the mainline, or haven't yet been integrated. If you're interested in the specific rtems source that went into various products Linn has shipped, you can get that here.

Product Software Version Rtems source
Klimax DS 1.0-0.48 RtemsKlimaxDs1.0-0.48.tar.bz2
Akurate DS 1.0-0.11 RtemsAkurateDs1.0-0.11.tar.bz2
Sneaky DS 1.0-0.6 RtemsSneakyMusicDs1.0-0.6.tar.bz2
(All Products) Cara 9 RtemsCara9.tar.bz2

Rtems is licensed under the GPL + linking exception. You can read the full license  here or in the source tarballs above.