I know therE are a couple versions out there that folks are working on, such as [MENTION=93857]C4[/MENTION].
Personally I don't think there's any use in recreating the wheel. And who wants to go over all the broken rules, and then get stuck in a debate about what is broken and what isn't? Is my version of 4.5 the same as yours? Maybe, maybe not.
Instead what I think the 4e chassis would be great for is an Ultralite 4e game inspired by something like Old School Hack (maybe a bit meatier) and focused on improvisational play. Something like that could operate on the premise that healing surges are essentially bennies that can be used to heal, to improve attacks, to get an extra attack or reroll an attack (replacing action points), etc. Each character class might have three feature options per level and you choose one. In addition, there'd be a list of power stunts and surge cost unique to the class like what [MENTION=80924]fjw70[/MENTION] and [MENTION=1165](Psi)SeveredHead[/MENTION] suggest.
Anyhow, I don't mean to knock anyone's ideas, it's just a huge amount of work and inherently involves value decisions that not everyone will agree on (e.g. Look at the "build of every role for every class" debate forming in this thread). I will add that I like a lot of these ideas as house rules for my own games and have actually implemented several behind the DM screen.
In particular, I use 6 types of monsters, not 3:
Minion - I include lots of homebrew tricks for my minions to increase longevity and fighting effectiveness without tracking; worth XP of 1/4 standard and sometimes 1/8 if it's a throwaway fight.
Humanoid - 33-50% HP of a standard, old damage expressions, simple mostly at-will powers,and worth half XP of a standard; used for small or medium sized creatures like gnolls, dwarves, orcs, goblins, etc.
Standard - use MM3 damage expression, reserved for quadrupeds, large monsters, or anything that isn't humanoid basically
Elite - As per the DMG2, for exceptionally strong enemies, usually named with some kind of unique lore to them, worth XP of 2 standards.
Champion - A powered up elite, a paragon of its kind or a unique monster of great age, inspired by [MENTION=714]frogsoth[/MENTION]'s "Savage" monster, usually a leader, has 2 action points, has some kind of action recovery, very nasty multi-attacks of typically high damage, saves at start and end of turn, an auto-damage aura or equivalent, free action attack when bloodied/dying, and other nastiness, worth XP of 3 standards
Solo - As per the DMG2, with action recovery and a whole host of other tricks that are too long to get into right here, possibly incorporating [MENTION=33187]gamefiend[/MENTION]'s "World Breaker", and [MENTION=14368]angryDM[/MENTION]'s "Three Stage Boss Monster", worth XP of 5+ standards.