Usual links
X-Wing guide to installing and playing: http://s93768914.onlinehome.us/xwing/
Module download page: http://www.vassalengine.org/wiki/Module:Star_Wars:_X-Wing_Miniatures_Game
Tip jar: http://s93768914.onlinehome.us/pub2/500release/index.html
Didn't we just have another release in June??!
Yes, it was 5.3.1, to make the Hound's Tooth (YV-666) playable, right after FFG's preview article for it.
Here are the details of that release, here: http://teamcovenant.com/mu0n/2015/06/16/x-wing-vassal-module-v5-3-1-available-now/
Ok, I'll bite, what's new here?

Small release, your v5.3.0 (and v5.3.1) squad files are (still) safe
This new v5.3.2 version pretty much adds the Kihraxz ship, dial and all of its 4 pilot cards. It also adds the Lightning Reflexes elite talent upgrade. It doesn't modify or remove anything important from v5.3.0.
If you're currently not interested at all by wave 7? Carry on with v5.3.0 (or v.5.3.1) and wait for a future, more important release.
If you're very interested by anything wave 7? Get this update, and the few next ones as FFG previews give us more functionality in working ships (as soon as dial information is released, as well as more upgrades). The next functioning ship or bunch of upgrade cards will call for a v5.3.3. It will be similar to v5.3.1 and v5.3.2 in terms of having to update to it - only if you're interested in using wave 7 stuff, or playing against it.
Starviper has a new look
Radarman5 thought it looked a bit too much like a frog, so he went back and edited his art. NICE.

Complete list of changes:
@Mu0n:
Additions
- Cards
- Cartel Marauder (Kihraxz Pilot)
- Black Sun Ace (Kihraxz Pilot)
- Graz the Hunter (Kihraxz Pilot)
- Talonbane Cobra (Kihraxz Pilot)
- Lightning Reflexes (Elite Talent upgrade)
- Dials
- Kihraxz dial, making the ship playable
New ship art:
- Cobbled together a Kihraxz Ship art from FFG previews
@radarman5:
New ship art:
- StarViper ship graphic edited to look less like a frog