Update (18th January 2015): the ECB now has new home: https://github.com/ecb-home/ecb
I already twitted about this, and also wrote to ECB & CEDET mailing lists, but I also want to reach Planet Emacs readers :-)
I made small changes in the ECB code that allow to use it together with fresh Emacs & CEDET versions. Modified code is available in my github. I tried this version together with CEDET from trunk, and also with CEDET from Emacs 24.1, and it worked for me.
If you're using ECB, please try this modified version, and leave feedback (either here, or by sending e-mail to me or to ECB mailing list). If you'll find bugs, feel free to file a bug using github's issue tracker.