The libdnet package was pulled in as a dependency by some package. result: bot my ubuntu machines had the same fake mac HWaddr aa:00:04:00:0a:04, that fucked up my network. I deleted the relevant packages (all that had anything to do with libdnet) and it works again.
DistroRelease: Ubuntu 11.10
Package: dnet-common (not installed)
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
Date: Wed Nov 9 00:46:46 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110426)
UpgradeStatus: Upgraded to oneiric on 2011-10-14 (25 days ago)