Did you have trouble viewing your “What’s Happening?” Twitter feed on June 25? Chances are, if you were barreled over by the Fail Whale that day, it was because news of Michael Jackson’s death was being typed out by users of the social networking service at lightning speed.

PC World has published Twitter’s Top Trending Topics Of 2009, and—no shock here—MJ wound up being the most talked about person in the past 12 months. Vocal (and sales) powerhouse Susan Boyle comes in just behind Jackson at #2. And Time can feel properly justified in singling out Adam Lambert as one of its 25 People Who Mattered In 2009—the glammed-up American Idol runner-up was the third most discussed person this year on Twitter.

Over on the hashtag round-up, #MusicMonday came in first, while #sxsw (or South By Southwest) landed at #3. So much for #FollowFriday, which didn’t even rank in the Top 10. American Idol and Glee topped the television topics.

Hop below the jump to see what other people, TV series, news events and hashtags made Twitter’s Top Trending Topics Of 2009.

PEOPLE

1. Michael Jackson
2. Susan Boyle
3. Adam Lambert
4. Kobe (Bryant)
5. Chris Brown
6. Chuck Norris
7. Joe Wilson
8. Tiger Woods
9. Christian Bale
10. A-Rod (Alex Rodriguez)

TV TOPICS

1. American Idol
2. Glee
3. Teen Choice Awards
4. SNL (Saturday Night Live)
5. Dollhouse
6. Grey’s Anatomy
7. VMAS (Video Music Awards)
8. #bsg (Battlestar Galatica)
9. BET Awards
10. Lost

HASHTAGS

1. #musicmonday
2. #iranelection
3. #sxsw
4. #swineflu
5. #nevertrust
6. #mm
7. #rememberwhen
8. #3drunkwords
9. #unacceptable
10. #iwish

NEWS EVENTS

1. #iranelection
2. Swine Flu
3. Gaza
4. Iran
5. Tehran
6. #swineflu
7. AIG
8. #uksnow
9. Earth Hour
10. #inaug09