Google has updated the Native Client SDK with several additions that should be of interest particularly to developers looking to port existing C/C++ applications. The new features, part of the Pepper 25 update, make it possible to run more code as is, without alterations or additions.
The other big addition is support for ARM processors. Developers can now create Native Client executables that work on ARM platforms, like the new Samsung Chromebook.
The new ARM-powered Chromebook was introduced only a few months ago, so Google moved quite fast to add support to the Native Client SDK. Granted, support for ARM was a day-one goal.
On ARM, Native Client apps don't have access to all the features available on the standard x86 platform, but it's a start.
Also new are two libraries. The nacl_mounts library provides a virtual file system so that applications can use standard C file operations. Native Client apps run in a sandbox and can't access the actual file system directly.
In that same vein, ppapi_main makes it easier to create Native Client modules by providing the equivalent of the main() C function.