Originally published August 04, 2010.
Information provided in this post may be out of date.
Update 2013-July-8: this workaround appears functional again with Eclipse Kepler.
Update 2012-July-12: this solution no longer works for me with Eclipse 4.x. And, I’m not the only one.
There’s an issue with pinning Eclipse to the Windows 7 taskbar on 64-bit systems. Fortunately one of the suggested workarounds does the trick for me.