My wild guess is:
* +1 to attack every 5 levels (starting at 3)
* +1 to two or three stats every five levels (starting at 5)
* stat bonus = stat - 10; that is Str 18 = Str +8
* +1 magic items at heroic, +2 magic items at paragon, +3 at epic
* +1 / tier inherent bonus for campaigns without magic items
* NO attack bonus from feats
This equals a +1 / 2 levels progression on the monster side, or about half the progression speed of 4E.
Classes are probably written in a way that you get a class feature, power, spell slot, bonus feat or similar every level. Multiclass characters can pick between their two classes at every level.
There is a second track where you get either +1 to attack or +1 to two ability scores or a racial feature or a theme feature or a feat (that's five categories, so one every five levels each)
Oh, and you'll get a combat style at level one, because that's just such a great idea
But as I said, it's pure speculation and we'll know more when the playtest material arrives.