On most servers, the Ability Bonus Cap from Items is +12, on Worlds of Rhun, to make better use of your items, players will be able to receive +30 Bonus from all their items together. This should make some of the Older Subraces more viable, and also make powerful items and artifacts less redundant.
On most Servers, you can only receive a +20 Attack Bonus, on Worlds of Rhun however, you 'should' be able to receive +30 without any major problems.
For all the Ability and Attack Bonuses, the cap's have increased to +30, however, the Decrease Cap has also been lowered to -30. Meaning if you were to be hit with enough Ray of Enfeeblements, you could loose 30 Inteligence etc.