The CUG (Cray User Group) conference in Helsinki assembles 150 Cray supercomputer users and administrators from supercomputer centers around the world. The present CUG 2008 conference is hosted by CSC, the Finnish IT center for science, administered by the Ministry of Education. CSC's most powerful supercomputer Cray XT4 (Louhi) was introduced a year ago. The event's theme is "Crossing the Boundaries", reflecting how improvements in computational science and high-performance computing have enabled coupled and cross-disciplinary simulations in many fields, such as Earth system science, nanoscience, biotechnology and various fields of engineering. The theme also refers to crossing the boundaries between academic and industrial research, development and optimization, as well as collaboration across national borders. At the opening day, the Keynote Speaker was Professor Ilpo Vattulainen, who’ s simulations made with CSC’s Cray supercomputer have produced significant new information on molecular biology. Computer simulations predict that altering the physical properties of cell membranes can regulate the activity of membrane proteins and hence, a variety of cellular processes. Biological cell membranes are extremely thin and complicated structures that comprise mostly various lipid molecules, proteins, and carbohydrates. Complex biological systems are characterized by a variety of length and time scales. The computational challenge to account for both atomistic and larger scales is particularly evident in lipid systems. The length scales range from nano-sized lipids to 10-25 nm-sized lipoproteins and further to micron-scale cell membranes. The means for bridging these scales through examples for a number of lipid systems are discussed, including domain formation in many-component membranes and the structural aspects of lipoproteins known as carriers of cholesterol. CUG 2008 takes place in Helsinki from May 5th to 8th. The first CUG was organized in 1978 and the current one is the 50th CUG conference, as well as the 30th anniversary.