L4

DROPS - The Dresden Realtime Operating System Project
L4 and Linux based research project aiming at the support of applications with Quality of Service requirements. At TU Dresden.
http://os.inf.tu-dresden.de/drops/overview.html

E1
A distributed operating system based on the concepts of object replication, component model support and persistence. It consists of a L4 microkernel and a set of distributed objects acting at the user level. [Open source]
http://www.e1os.org/

Fiasco
Preemptible, realtime, 2nd-generation microkernel, fast, maintainable, readable, supports hard priorities, uses non-blocking synchronization for kernel objects to guarantee priority inheritance, ensure runnable high-priority processes never block waiting for lower ones; rework of L4 interface. [Open Source, GPL]
http://os.inf.tu-dresden.de/fiasco/

The Hurd on L4
Porting the Hurd to the L4 microkernel. News, plans, pointers to mailing lists and websites.
http://www.nongnu.org/l4hurd/

L4 Microkernel
L4/MIPS: stable L4 for MIPS R4x00 processor, may be fastest kernel for this architecture. L4/Alpha: begun at Technical University of Dresden, SMP version released. Linux ports: L4/MIPS, L4/Alpha underway.
http://www.cse.unsw.edu.au/~disy/L4/

L4 Microkernel Family
Growing article, with links to many related topics. Wikipedia.
http://en.wikipedia.org/wiki/L4_microkernel_family

L4/Darwin: Darbat
Experimental port of Darwin to L4 to study traits of large-scale microkernel-based system; has port of IOKit to L4, modified libc to communicate to Darbat Server, XNU with many machine-dependent parts highly modified. National ICT Australia.
http://ertos.nicta.com.au/software/darbat/

L4Ka Project
L4-based microkernel systems, for embedded systems to huge servers; Pistachio kernel. L4: tiny, fast, 2nd generation microkernel using hierarchical external pagers and guarded page tables. Goals: create, prove, establish new methodology for systems that helps manage growing complexity, minimize legacy dependence.
http://l4ka.org/

Mungi
Orthogonally persistent, capability-based secure SASOS using L4 2nd generation microkernel. Goals: Prove SASOSs can run on normal hardware, be as secure as normal OSs; can be as efficient as, and are faster than, normal OSs in some important uses; can be pure SASOSs with all data (even system data) in one address space and no other IPC mechanism is supported by OS. POSIX emulating. [Open Source, GPL]
http://www.cse.unsw.edu.au/~disy/Mungi/

Perseus
A secure platform for applications that use digital signatures. Based on L4 and Linux. Research project at Applied Data Security Group, Ruhr-University Bochum., Germany.
http://www.perseus-os.org/

SourceForge: L4Ka Microkernel
The L4Ka microkernel is an L4 compatible kernel running on many platforms: ARM; MIPS; 68k, PPC; x86. A port of Linux atop an L4Ka microkernel exists.
http://sourceforge.net/projects/l4ka/

Virtualised OS: Wombat
Experimental port of Linux to run on L4/Iguana; is not intended to be standalone, best used as part of Iguana project. National ICT Australia.
http://ertos.nicta.com.au/software/kenge/wombat/latest/