Linux supports full System V IPC. However, it does not, and probably
never will, support TLI or STREAMS because both are inefficient
without severe abstraction-barrier breakage.
Just to make sure everyone understands this issue....
TLI is typically implemented over STREAMS, but it doesn't have to be.
In fact, TLI looks a lot like the Berkeley Sockets API, except of course
AT&T had to make some gratuitious changes just to make sure it was
incompatible. It is possible to write TLI emulation library which
emulates the TLI calls by making the correct BSD Socket calls; there are
a number of these floating around, which other people have pointed out.
TLI support can be done, but it's probably best done at the libc
level.... (which is why I cc'ed the linux-gcc list; please direct
followups to the correct list, depending on whether you want to comment
on kernel issues or libc issues.)