Twitter got 'Grey's Anatomy' fans very excited this week, but were the tweets misleading?

'Private Practice' star Kate Walsh and the shows' creator Shonda Rhimes were all a-tweet about Walsh being back on the 'Grey's' set to shoot. But it's not another crossover episode (although Rhimes promises there will be one again soon) -- Walsh's Addison is there to reunite with her TV ex Derek (Patrick Dempsey) for a "what if?" episode.

TV Line is reporting that a very special February sweeps episode of 'Grey's' will see the gang at Seattle Grace in an alternate reality. A very alternate reality, one where Meredith (Ellen Pompeo) isn't so dark and twisty, her surgical pro mom Ellis (Kate Burton) never got Alzheimer's and -- brace yourselves, MerDer diehards -- Addison and Derek never broke up.

AOL TV has learned that Shonda Rhimes' newest ABC series, 'Scandal,' will share a lot more than a creator in common with the network's medical soaps 'Grey's Anatomy' and 'Private Practice.'

Many of the guest stars booked to appear in the first season of 'Scandal,' which is scheduled to debut in early 2012, have also roamed the halls of Seattle Grace. Kate Burton and Jeff Perry, otherwise known as Ellis and Thatcher Grey, will both play Washington D.C. higher-ups in the new series, which stars Kerry Washington as Olivia Pope, a PR crisis management consultant who specializes in ushering politicians and other celebs through very public scandals.

Burton will recur as the Vice President starting in episode 5, while Perry plays the White House Chief of Staff. JoBeth Williams, who played Addison's mom on 'Private Practice,' will appear as a major client during the series' third episode.

'Celebrity Apprentice' star and original 'Survivor' winner Richard Hatch is heading back to prison.

According to the The Hollywood Reporter, Hatch will serve nine months in jail for failing to pay taxes on the $1 million he won after the first season of 'Survivor.'

Hatch, who is currently appearing on NBC's 'Celebrity Apprentice,' served more than three years in prison for tax evasion. He was released in 2009 and was on a three-year supervised release.

The reality star was supposed to re-file his 2000 and 2001 taxes and pay what he owned. However, he never did. Hatch now owes more than $2 million to the IRS.

In other TV news ...

• Kate Burton has joined the cast of NBC's 'Grimm.' The veteran actress will play the main character's aunt in the cop drama where fairytale characters are real. She's billed as a special guest star and could recur if the pilot goes to series. [TVLine]

• Tom Sizemore will star opposite Ethan Hawke in 'Exit Strategy.' Eric Winter has also joined a pilot, Fox's 'Weekends at Bellevue.' [Deadline]

• Discovery Channel has ordered a special on the Japanese earthquake and tsunami. 'Anatomy of a Disaster' will feature footage and highlight the aftermath of the disaster. ABC's '20/20,' 'Nightline' and 'World News' will also air specials. [Entertainment Weekly]

'127 Hours' actress Kate Burton and noted opera star Renee Fleming are heading to 'Law & Order: SVU' for guest spots in the show's upcoming 'Bully' episode.

According to a source close to the set, Burton will play Annette, the "bully" in the episode. Burton's character is a wicked boss whose business partner is murdered.

Opera star Fleming's voice will be heard as the mother of one of the victim's co-workers. The character is a former opera star and plays a key role in the episode.

Where have I seen her before? The answer: everywhere. Here are eight of the hardest working character actresses on TV. Inspired by Eight Character Actors You Need to Know in Details, we present two quartets of women whose faces, at least, are familiar. After reading this, you won't be excused from calling any of them "Oh, her!"

Alison Brie – Classically trained at CalArts and still in her 20s, Brie specializes in "uptight and highly strung." She plays the prim Annie on 'Community,' but might forever be known as the sensible wife Pete Campbell doesn't deserve on ''Mad Men'.

Like a true character actor, Brie knows that the physicality of her roles is what helps her distinguish between the two. "Trudy has a different walk, she has a different voice. Annie carries herself differently, walks faster, does some things higher pitched, you know," she told TV Squad earlier this year.