How can I determine the version of Ant coming with Eclipse?
You can do so by typing the following command:
ant -version
In the About Eclipse -> Eclipse.org button -> Eclipse.org Plug-in Details you will see Apache Ant plugin with version information
Although TigrisCs answer will give you the installed Ant bundle version, this version is not neccessarily the version you're executing your Ant files against. The dialog where you find the Ant version that is used to execute Ant files you'll find under Window->Preferences->Ant->Runtime
HTH Tom
Inside your ant script the ant.version
property holds the information, if you need programatically.