Fighters and mages now use the same power system and have the same attack/save bonuses
Just for the record, it's actually not the case that fighters and mages have the same attack bonus.
Fighters have a higher attack bonus with weapons (because they use Weapon powers that are STR based, and have high STR). Magic-users do not (even with daggers and staves, M-Us don't have very good STR, and so don't have very good weaopn attacks).
The converse of the above is true for implement attacks (ie spell casting). Fighters typically aren't so good - and especially won't be good at Wizard attacks, which are INT-based, because few fighters will have very high INT.
One exmample of the practical relevance of this: in my 4e game I routinely have monsters run past the wizard. The wizard in my party is a Tome wizard, and doesn't even carry a weapon. He takes his OAs with his Tome as an improvised attack (+0 prof bonus, +0 STR, +5 level for a total +5 to hit for 1d4 damage). One time he needed exactly 20 to hit, rolled it, therefore got a crit, and out of sympathy I let him do his Tome crit damage (+2d10 fire) even though by the rules he's not entitled to it. This was the only time the wizard ever killed a creature in melee combat - I can't remember for sure, but it may be the only time he ever hit a creature in melee combat!
The fighter, on the other hand, has +1 class bonus with two-handed weapons, +2 prof bonus for his halberd, +4 for 18 STR, +3 for his magic axe and +5 for level - at total of +15 to hit for something like 1d8+11. His 16 WIS means he is +18 to hit on OAs.
The wizard and the fighter certainly do not have the same attack bonus. (What has changed is the build rules whereby that bonus is derived, and also the build rules whereby the ACs of the enemies against whom attacks will be made are derived.)