Let's just have a quick run down of the jungle masteries that I'll be using for the Season 3 jungle. Please take note that this doesn't cover the more specialized masteries I will be taking for some junglers like Diana and Gangplank but they are general suggestions to help give a starting point for most junglers.
AD Carry/Assassin Build
This one should be rather self explanatory and pretty simple to understand. There isn't much complexity here when it comes to the build. You increase whatever makes you do more damage with your auto attacks or your AD scaling abilities. It's rather straight forward. The offensive tree does not give any real utility or survivability thus it's mean for straight out killing machines.
This build has one free mastery point at tier 3 offensive. That point sticks out and it's on havoc. You can put that one point wherever you want but you need it to advance to the next tiers.
This one too is rather easy to understand. However there are a few masteries that are left unfilled and it will throw people off. That said, it is very likely that the bruiser build will have small differences between players as a lot of the masteries are very good but there aren't enough points available to capitalize on all of them. The lower tiers are saturated with masteries that require multiple points yet you open up the next tier which has even better things to put points in. It almost feels like a waste really.
It would be wise to consider what the champion prefers before you choose which masteries to take. What I mean by that is - does your champion prefer resistances or health? The crowd control reduction is basically a given on pretty much all bruisers
The build has 9 "almost" free points in the offensive tree. Depending on the champion, you either take the armor pen mastery or the magic pen one and essentially spend all your remaining points.
Support Tank Build
This one is rather fun actually. Take note that this build leaves the tanks rather squishy as they didn't take any relevant tanking masteries but it opens up a lot of power in utility. It basically grants the tank a load of cooldown reduction on abilities, items and summoner spells and even gives them increased mobility. Along with that they also get 2 free (if albeit weak) items to help out their fragile early clearing.
It is important to note that this build can also be taken by non "main" tank characters like Olaf as the utility tree is just that good. With that said though - taking these masteries basically makes it so the jungler HAS to receive aid from their teammates early on.
It has 3 free mastery points in the utility tree. You don't exactly need recall, the biscuit or the bonus ward. You can relocate that to the spell vamp if you need to but most tanks don't make good use of spell vamp or life steal anyways.
Pure Damage Caster Build
This one is also very straight forward. Basically think of the AP version for the AD build. The junglers who are FORCED to take this basically need as much killing power to annihilate a camp before it beats them to a pulp. The AP junglers who take this but aren't FORCED to will speed up their clearing speed and murdering power. There really isn't much to say about this one. It's basically a mirror of the season 2 pure caster build aside from the addition of spellsword which isn't all that great on some characters.
Full Tank Build
Just think of the bruiser build but with taking a dip into the utility tree for the extra goodies. Now it ends up having the same issues as the bruiser one where the defense tree is saturated with a lot of stuff you'd want points for but don't have enough. The thing with this build though is that it has 9 free points. Yeah that's right - it has 9 free points. The 9 points in the utility tree aren't completely necessary and you can toss more into the defensive tree to grab all the masteries you can't pass up to miss.
Yes this will give you a weaker early game but some of the tank masteries have multiplicative effects. That means that as the game goes on - they end up being better than what the utility tree would provide anyways.
AP Utility Build
This one is rather variable. It has 9 free points to go anywhere but the utility one is rather core. Much like the masteries for the support tank - this one is trying to make use of the glorious sexiness of the utility tree. However there is one thing to take note of - instead of taking any of the extra items or the experience mastery (or finishing the item cooldowns), the player takes the wealth masteries instead. The reasoning for this is to be able to buy an early FLASK and use it instead of potions (along with the machete). This is to avoid wasting any gold on potions for the entire game. It grants the champion some utility with increased gold efficiency. It isn't much different outside of that really.
The champions most likely to take this build are - Zyra, Elise and Cho Gath
There are other champions with more specific builds and they will be covered later as they get tested out and worked on. Enjoy the season 3 jungle!