First, if you are running android tools 8.0.1 from eclipse than everything works fine. Second, to run build using android tools 8.0.1 or higher outside of eclipse you must use ant 1.8.1 or higher. Most Linux version in theri beta/test repos already have compiled ant 1.8.1 binaries to install to run ant 1.8.1 form the command line.
My AndCooperANT set of build is being kept pre-ADT8, the new ADT8 or higher project is named IndianaANT and will be up in days.
Now for some other good news, it appears that ADT 9.0 may be pushed out December 20th as it fixes some minor bug issues. One of the changes is an ant version check in the custom task.
As far as eclipse, it will not have ant version 1.8.1 until very late in the 3.7 testing cycle and I doubt if eclipse 3.6.2 will include ant 1.8.1. Thus, since ADT 8.0.1 runs fine in eclipse without ant being upgraded in eclipse the best option is update your ant install if you run builds outside of your IDE. If you have not switched your build run outside of IDE to ant 1.8.1 you will notice the side effect of 3rd party libs not being included in the dex and that is due to some behavior changes between ant 1.7.1 and ant 1.8.1.