I read Old man's War and I'm reading Ghost Brigades. Listened to his After the Coup from Tor.com (set in that 'world'). There's a novelette, The Sagan Diary, and a 4th novel, Zoe's Tale.
He won the Campbell as best new sci-fi writer of 2005.
Both Old Man's War & The Last Colony were nominated for the Hugo.
Scalzi won the 2007 Hugo last night as 'Best Fan Writer' for his work about sci-fi at his blog whatever.com and at AOL.com and at amctv.com.
He's suddenly at the forefront of new sci-fi writers.