Microsoft this week <A HREF="http://news.zdnet.com/2100-9588_22-5606889.html?tag=zdnn.alert">lost a key software engineer to Amazon.com,</A> following another recent departure to Google. Pat Helland, a longtime Microsoft software developer, announced last week through his blog on Microsoft's MSDN developer network site that he left the software giant on March 4 and planned to start at Amazon on March 7. Microsoft's loss of Helland followed news of another departure. Marc Lucovsky, Microsoft's "distinguished engineer" who headed up a group working on the company's .Net technologies, now works for Google, the search company confirmed.