Since the forum hamsters got replaced lets try this again. 
The thing is I wish Beghins would put change logs in (some mod communities are like this but what can you do).
8.1 fixed a few energy issues and stability things (all I saw was energy being weird in 8.0). 8.2 is out on 24th or little after since mod dates are never set in stone so expect later. If you want to download faster get a download accelerator (Download Accelerator Plus 20-30mins to download). Also complex 8 should run a little faster 5-10%, they did some code cleaning.
I'll break it down.
1. Energy- If you played Supreme Commander you'll get the idea. You now have a new resource to manage if your good at it your production gets a boost and same with your engines on your ships (the production boost is bigger than the engine boost), if you don't do a good job at managing it your production goes down the toilet. Higs- powerstation and production ships have slots to increase power production and storage. Higs also get 3 techs to boost power slots output and they are expensive (later down the road there will be power abilities ie complex 9). Vay- research better power and some productions ships get power slots. Fighting takes a toll on your energy. Building too much can hurt your energy too and slow you down. Also the power station can be a double edged sword ie more power slots on it the bigger the explosion when it goes so watch it! Also if your energy economy goes to hell your power station will slowly die and then explode ie no power in storage left!
2. Rebalance- (this is still being done) crap load of testing and 8.2 will add more balance changes. Basically Officer and crew counts rebalance, ship counters, master strategies, ship stats being looked at (speeds, weapon damage, etc…), finally fighters and corvettes are better in the end game, frigates got some love too (they are still being looked at), If certain ships were lacking they got buffed, ship pricing, certain ship textures/ assets got replaced ie new X Bomber model, etc... Carriers are better all around which is nice (faster and more health). Certain abilities/ships are unlocked a certain ranks. Vortex got nerfed (no longer the perfect pocket battleship and yes it did exist).
3. New ships- New carriers for both sides, new vaygr fighters, new corvettes both sides, new frigates, new support ships (I play more Hig than Vay so sue me if I forget something...), new Heavy Vaygr Destroyer, new Vaygr Dreadnaught replacement, new hig platforms (Yaygr platform ideas forming), new utility ships both sides, new stations for Higs, ah ya lots of stuff...
4. Few new maps and a new game mode which takes place in a solar system (you can capture planets and also have a civilian crew to manage). You must watch out for radiation when expanding! This is a really slow game mode and only higs can play it at the moment.
These next few things are either coming in at 8.2+ or going in Complex 9. I don't know because I'm a tester and not a developer.
Tech tree getting some love and a cleanup job. Saw a preview on it and it looks better. Some techs get tied together. More tech too. Fixing descriptions.
New formation system coming.
Ya I am forgetting some other things too. Complex 9 will have a campaign, 3rd race progenitors, Hig Dreadnaught (finally!), etc... Complex 9 date late 2012 or 2013 (bet on 2013).
