Unity 5 update is coming soon(tm), the content branches besides the stock remote tech/comm relays are not ready for experimental yet, but we'll get Unity 5, the relays and some new parts in 1.1 before those other currently unrevealed branches get finished.
Key changes:
- Multicore physics simulation for a single vessel. Yes, that means all that crazy 400 part shit is going to melt not one but all of your CPU cores now.
- Possibly stable 64-bit for Windows and OSX.
- The mentioned comm relays for probes and SCIENCE.
- a few new stock parts from Porkjet, including a spaceplane cargo-bay with a deployable rover ramp (oh how I longed for this part!), plus a remake of the jet (duh) engine art assets, the mk1 spaceplane cockpit, oh and probe-sized jet engines and jet fuel tanks plus a mk3 sized jet engine.
- contextual contracts (hey you have a space station with a docking port, why don't you build a lab module and attach it to it) - not sure if in 1.1 or they will be later.
Another one of the modders got assimilated into working on the game, NathanKell. He's currently tasked with fixing mod-support related bugs and optimizing that part of the code.
Meanwhile this is what Porkjet did that we'll have in 1.1:
Yes, you can now kind of remake that ship from James Bond, which stole kwan and soviet spacecraft, with stock parts.
New fighter-like high agility vectoring jet. It has afterburner capability.
This is what Jeb flies to work nowadays, when he's out of rockets.
New mk1 cockpit and passenger cabin (finally!)
New small engine with small intakes. Perfect for your Laythe drones and/or jet VTOL shenanigans.