On of our goals for approaching Test::Harness 3.0 is to see just how many bugs we can eliminate from the current Test::Harness RT queue. As of today, out of 54 bugs (ignoring the spam entries), 10 are fixed and 14 do not apply to the current architecture. In other words, almost half of the current T::H bugs are gone. Work progresses on the others.
Also, it looks like we'll have the new TAP syntax supported, even though there might not be a new TAP producer at the time of release. The new, fully backwards compatible TAP may very well resemble the following:
TAP version 13
not ok 4 foo is bar, dammit!
test: is $my->foo, \@bar, 'foo is bar, dammit!'
name: foo is bar, dammit!
That's just an example and is is unlikely to exactly match the final syntax, but it does mean that TAP will finally have machine readable diagnostics available (yes, you'll be able to have diagnostics with passing tests, too).
Andy Armstrong is also looking at separating the internals into an MVC framework to make it easier to control the output. After that, internationalization should be pretty easy.