I received a Twitter DM from one of the accounts that was a victim of Twitter phishing this weekend.

Hey! I just got a FREE iphone from this website.. here
http://helloiphones.com

The culprit is a follower known to me, and not a random spam follower this time.  Looks like some other people are experiencing the same thing, according results found in Twitscoop:

Just received a DM from an actual follower. helloiphones.com So not clicking th@, & delete! My 1st phish. Watch out 4 it Twitteropolis.

Added 2008.01.05:

An InformationWeek Article mentions that some hacked accounts were compromised by someone who hacked some Twitter support tools.