Yes, it was moved from the Labs section of Google Webmaster Tools to the Diagnostics section. Malware details has officially graduated from Webmaster Tools Labs. I believe this may be the first feature in the Webmaster Tools Labs that graduated.
JohnMu confirmed the change via Twitter saying:
@RalphMRivera @rustybrick @websonic : The malware details are now under "diagnostics" in Webmaster Tools, graduated from Labs :)
Forum discussion at Google Webmaster Help.
Note: This was written Sunday, April 4th and scheduled to be posted today.