I know quite a bit about the progression of harmony during the common practice period and up to basic jazz theory, but anything beyond the early 20th century just drops off for me. I know a little about serialism, but even that seems a little dated. Are there modern movements in harmony that go beyond these ideas? And are they being studied on an academic level yet? It seems like a lot of schools of music are just starting to recognize jazz theory and yet I really want more modern material to study from.
One of the central harmonic (and melodic) innovations of early 20th-century music was the conflation of the linear and harmonic dimensions. That is to say, a collection of pitches might just as easily be a motive or a melody as it might be a chord. In the common-practice world the linear, melodic dimension tends to be dominated by whole and half steps while the harmonic dimension is mostly built out of thirds and fifths. Under the new way of thinking, if my main melodic motive is E–G–Eb (as it is in the eighth movement of Schoenberg's Pierrot Lunaire) then my harmonic soundscape might be composed of minor thirds, major thirds and half steps just like the motive.
The primary method for studying the harmonic/melodic possibilities is set theory, as mentioned in another answer. That answer suggests The Structure of Atonal Music, which is well worth reading. Personally, I would recommend Joe Straus's Introduction to Post-Tonal Theory, because I think it's clearer and it also has chapters on other topics that will further address your question.
You mention serialism, which is also covered in the Straus book. If your primary interest is in studying new harmonic ideas, then serialism won't really provide. It's more a method for building larger scale connections into your pre-compositional palette. It can be quite useful, but the harmonic options at the local level (as opposed to global concerns of an entire piece reminiscent of key areas in common-practice tonal music) are the same as those covered in studying set theory in general.
Another trend that composers looked into relatively early in the twentieth century is the kinds of harmonies available under completely different scales. Look into the octatonic scale, the hexatonic scale, various modes of the harmonic and melodic minor, while-tone scales etc. Bartók and Stravinsky have lots of works in this vein. Lots of that is also covered in the Straus text.
If you really want to explore wildly different vistas of harmony you might like into Spectralism and Extended Just Intonation as well as other microtonal worlds. Spectralists like Grisey and Murail compose harmonies based on the harmonic overtone series in order to create all kinds of eerie effects. Grisey has a piece called Partiels in which the entire orchestra gradually tries to emulate the sound of a bass trombone playing a single pitch. Extended Just Intonation pieces like the string quartets of Ben Johnston are also deeply interested in the overtone series, though in a different manner. Here's an introduction to just intonation by Kyle Gann that might get you started: http://www.kylegann.com/tuning.html
Anyway, that's a potpourri of some of the major harmonic movements of the twentieth and twenty-first centuries. I'm sure others will provide more avenues to explore.
Are you familiar with pitch-class set analysis? The pioneering work was done by Allen Forte in his books, The Structure of Atonal Music and The Harmonic Organization of The Rite of Spring. If you can get hold of it, John Rahn's book Basic Atonal Theory presents Forte's ideas and methods in a much more user-friendly manner. The basic idea is to convert pitches to their numeric equivalents (0 through 11) and group these into sets based on their melodic and vertical proximity. With this method we begin to see much more deeply into the fabric of a musical composition than methods based on conventional harmonic analysis.
If you are looking for Jazz theory, The Lydian Chromatic Concept by George Russell would be a great starting point. The original came out in the early 1950's and it was extremely influential on players like Miles Davis. It is often credited with being one of the primary inspirations for later movements in jazz, especially modal jazz.
Rock, blues, and heavy metal work under their own harmonic precepts both separate and distinct from jazz, but there is little if nothing in the way of theoretical texts on the subject, what little there is must be gleaned from method books and songwriting "manuals", or of course the recordings themselves.
And are they being studied on an academic level yet?
Jazz is being studied on the academic level, however, given the current climate in academia, most research is released as papers in academic journals rather than being compiled into one magnum opus.
Try searching Google Scholar or the equivalent to locate them.