For my interest and somewhat deeper knowledge in watermarking especially of audio content, I found the following talks very enlightening (in order of the conference):

• Supraliminal Audio Steganography by Heather Crawford and John Aycock: Although their approach to audibly hide information in audio files using sounds from the domain resp. genre of the audio content itself is far from being perfect at the moment, it seems to be a promising approach for steganography at the semantic level that could prove quite difficult for conventional steganography to detect.
• An Epistemological Approach to Steganography by Rainer Böhme: A very illustrative discussion of the empirical nature of steganography (and also other disciplines of information hiding) and the need for a separation between models of the steganographic channels and the steganographic algorithms themselves.
• A Phase Modulation Audio Watermarking Technique by Michael Arnold, Peter G. Baum, and Walter Voeßling: Using a watermarking method modulating phase information in the Fourier Domain, the authors attacked the challenge to actively measure audience rates for broadcast media. The MPEG psycho-acoustic model is used to determine embedding thresholds in order to ensure maximum audio quality.
• Perception-based Audio Authentication Watermarking in the Time-Frequency Domain by my co-workers at Fraunhofer SIT, Sascha Zmudzinski and Martin Steinebach: The integrity of audio content is protected by extracting features forming a robust perceptual hash that is in turn embedded into the content itself using a watermarking technique. This way, the authenticity of the content can be verified, even after common processing such as lossy encoding or analogue transfer.