As of writing, the block has been removed and users will no longer be prompted by a scary malware warning when trying to access Twitter from their browser.
TwitPic was quick to let users that the issue was a false positive:
Working to fix the google chrome malware notice when visiting Twitpic.com as this is not true or the case, trying to contact google
-- TwitPic (@TwitPic) December 30, 2012
At the time, this is what you were prompted with when heading to TwitPic (via TheNextWeb):
Written by: Andre Yoskowitz @ 30 Dec 2012 21:55
