Well the IDF released it's "findings" concerning the "accidental" shelling and air-strike that killed for UN observers... and the conclusion is: that IDF was using a hand-drawn map to plot it's artillery battery and air-strikes
http://www.cbc.ca/story/world/nation...el-report.html
Anyways since my opinion is obviously bias (apparently like everyone else who questions some Israeli actions), I'll let others with military experience or knowledge comment on the likelyhood of a hand-drawn map countering GPS positioning, Laser guidance, and 20+ years of maps showing the UN post (and former Israeli post before that).