The newest build is 0.1.3. You can download it here.
This download contains source code that is subject to the U.S. Export
Administration Regulations and other U.S. law, and may not be exported
or re-exported to certain countries (currently Afghanistan (Taliban
controlled areas), Cuba, Iran, Iraq, Libya, North Korea,
Sudan and Syria) or to persons or entities prohibited from
receiving U.S. exports (including Denied Parties, entities on the Bureau
of Export Administration Entity List, and Specially Designated Nationals).
If you plan to mirror this download read our crypto FAQ.
Chimera has complete build instructions on mozilla's Web pages (under the code name ChimChim). You can find those instructions here. Be aware that the downloadable build listed above contains numerous patches to Mozilla that have not yet been accepted, so any builds that you do will not be as stable or as performant as the downloadable build above.
If you have questions about building, use the chimera mailing list or hop on to #mozilla, and someone can help you out.