Paradox have dropped update 1.2 Asimov and hotfix 1.2.1 for Stellaris. It has some interesting new features. For instance players can now enter an empires borders until closed by diplomatic actions. Also included are new nomadic fleets and varied population factions. Also, the Borg have been updated, rejoice! If you don't want to get the new update, simply switch to 1.1.0 branch on Steam. Here's a quick list of the changes in the new update:
Colonising planets and building outposts now costs influence
Embassies are replaced by building long-term relationships with other empires via trustworthy actions.
Diplomacy interface includes additional actions, options and diplomatic incidents.
Additional changes to various ethics, government types, reworked slave factions and end game crisis boost.
removed embassies and replaced it with trust
borders are now open to everyone by default
diplomatic incidents added to enrich mid-game content
new war goals added
new defensive pact option
solar systems received new backgrounds
fleet behavior improved for better looking space battles