Prior to the patch, each NPC corporation had up to 21 divisions (security, distribution, etc.), each with agents that gave out different types of missions. CCP Molock notes that "these divisions and values did little other than adding complexity to an already complex game," and the devs have condensed said divisions into a more manageable set of four: distribution, mining, security, and research. The tweaks necessitated the removal of the game's seven connections skills, which were then replaced with three new skills (distribution connections, mining connections, and security connections). Players who had previously trained connections skills will find their skill points refunded.
EVE's agent quality system was also a bit of a puzzler for both players and devs, and Molock says its "effects were not particularly meaningful." CCP is reassigning both a -20 and a +20 value to all the game's agents, which will effectively make it easier to access many of them as well as raise their payouts. Further details are available via the full dev blog at the official EVE website.