Over the years, polymers have attracted a great deal of interest because they offer a unique platform for the development of materials in fields as diverse as biomedicine and packaging. Many of these purposes use polymers that had been developed for totally different applications. Recently, however, chemical tailoring and molecular and supramolecular control of the chemistry and, thus, the physical and biological response have become a key interest of many researchers. In particular, systems that operate in aqueous media have become an intensely researched field. This is mostly because many devices must be biocompatible, which implies that they have to function in aqueous solutions. Over the past few years, new approaches for mimicking cell surfaces, for generating biocompatible and bioactive drug delivery systems, and for directed targeting have been developed. One recent development is polymeric systems with an enhanced biofunctionality, such as amphiphilic block copolymers that can act as mimetics for biological membranes. Because there are virtually no limits to combinations of monomers, biological and synthetic building blocks, ligands, receptors, and other proteins, polymer hybrid materials show a great promise for applications in biomedicine and biotechnology.