Top Trending Terms on Twitter 2009

In order, although 'the order is dynamic'
1 - #iranelection
2 - #musicmonday
3 - Michael Jackson
4 - Google Wave
5 - New Moon
6 - Follow Friday
7 - Halloween
8 - Paranormal Activity
9 - Harry Potter
10 - TGIF
11 - BBC
12 - BBQ
13 - Swine Flu
14 - District 9
15 - Susan Boyle
16 - Star Trek
17 - Snow Leopard
18 - Lakers
19 - #SxSW
20 - American Idol
21 - Glee
22 - Adam Lambert
23 - Easter
24 - Watchmen
25 - True Blood
26 - Dollhouse
27 - #openwebawards
28 - Goodmorning
29 - Lady GaGa
30 - Kobe
31 - VALENTINE'S DAY
32 - Nfl
33 - SUPER BOWL
34 - Wolverine
35 - CNN
36 - AIG
37 - Bruno
38 - Thanksgiving
39 - Oprah
40 - Mexico
41 - SUMMER
42 - Chris Brown
43 - SNL
44 - Palm Pre
45 - MIAMI
46 - Paris
47 - California
48 - Transformers 2
49 - MW2
50 - CES
[By my reckoning 21 relate to entertainment-based brands or words, including names of TV shows, films, and musicians. Tells you a lot about the twitter audience.]
Source: AdAge, 17th December 2009, citing data from What The Trend's Zeitgeist