Well, there are Birds of Paradise on Ravnica. I'm sure you can wait the 0 seconds it won't be legal in Standard if it returns in Return to Ravnica. Otherwise, I guess you'll have to handle playing some other cards in Standard.
I really like Vile Rebirth. A lot. It's a great, flavorful option that adds something unique to a Zombie deck of any kind while providing a nice way to counter some of the graveyard shenanigans that might occur. We do lose both Surgical Extraction and Nihil Spellbomb, so it's nice to know that they gave us Vile Rebirth and Tormod's Crypt to provide some graveyard hate options.
Constructed Sleeper so far: Quirion Dryad. This card is absurd with Snapcaster Mage, and with the coming tide of multicolored cards, Quirion Dryad might prove to be a powerful addition to RtR Standard. I'd keep an eye on this one. Honorable Mention: Slumbering Dragon. I mean, come on, it's actually asleep.
Also nice to see Silklash Spider once again in a Core set. Silklash Spider is an old favorite of mine, and I can't wait to get the chance to slot it into a few sideboards.
And now time to go work on my Trading Post deck list.