Patch 1.0.3 deployment. For reference, here are the scheduled maintenance times for each region:

The Americas: 3:00 a.m. PDT (6/19) to 1:00 p.m. PDT (6/19)
Europe: 6:00 p.m. PDT (6/19) to 4:00 a.m. PDT (6/20)
Asia: 1:00 p.m. PDT (6/20) to 11:00 p.m. PDT (6/20)

Please note that these times are subject to change. Note that, if your home region is the Americas, you will be unable to log into Europe or Asia using Global Play after patch 1.0.3 is live until those regions have also patched.

Blizzard is going to perform a server maintenance tonight to deploy the 1.0.3 patch. A lot of changes will implemented and a lot of changes I was really looking forward to. I’ll mention a couple that are interesting to me.

Improved Drop Rates

The drop rates are going to get bumped up! Meaning there’s a probability of high level gear dropping in Hell Act IV (up to level 62), and Inferno Act I & II. Currently, the only way to get gear good enough to beat Inferno Act II is to party up with people or buy high level gear in the Auction House; which drops in Inferno Act III & IV ironically. This change will help a lot of people, including myself, to get awesome gear without grinding and farming for hours and hours.

Nephalem Changes

“It’s no secret that our goal for the end-game item hunt is players hunting monsters packs, building to five stacks of Nephalem Valor, and then killing a boss. While we’re seeing a lot of that occurring, what we’re missing is people feeling like it’s worthwhile to continue onward after killing a boss.”

Completely true! Everyone is rushing for the 5 Nephalem stack and then going for the boss kill to get the Rare loot. The Butcher run is a great example. In the 1.0.3 patch, the guaranteed Rare drops will be lowered from 2 to 1 from bosses (multiple Rare drops is still possible, just not guaranteed). Additionally, all champion and rare packs will not drop an additional Rare item when you have 5 Nephalem Valor stacks.

Nerfing Inferno

Oh yeah baby! Act II, III & IV will be nerfed by adjusting the damage and health of the monsters. Melee class (Monk & Barbarian) have quite a hard time going through these acts, because you have to switch your gear to a more defensive build. It’s very hard to survive with an offensive build since the monsters will just one-shot you. Act I is in a pretty good place and Blizzard wants to smoothen the difficulty curve in the other Acts.

Conclusion

These are basically the more interesting changes that will affect me continue playing the game. There are more changes in the upcoming patch, such as increased repair costs, lowered jewel and blacksmith training, and many over improvements and enhancements. For a more detailed list of changes, visit the Blizzard official post [link]

Sources:
http://us.battle.net/d3/en/forum/topic/5837135682
http://us.battle.net/d3/en/blog/6262208
http://wow.joystiq.com/2012/06/19/diablo-3s-patch-1-0-3-releasing-today/