10 Challenging Problems in Data Mining Research

On ICDM'05, Qiang Yang and Xindong Wu presented 10 Challenging Problems in Data Mining Research.
1. Developing a Unifying Theory of Data Mining
2. Scaling Up for High Dimensional Data and High Speed Data Streams
3. Mining Sequence Data and Time Series Data
4. Mining Complex Knowledge from Complex Data
5. Data Mining in a Network Setting
6. Distributed Data Mining and Mining Multi-agent Data
7. Data Mining for Biological and Environmental Problems
8. Data-Mining-Process Related Problems
9. Security, Privacy and Data Integrity
10. Dealing with Non-static, Unbalanced and Cost-sensitive Data

I am particularly interested in Problem 2, 4 and 5 which share one common theme: Learning/Mining with Very Large Graphs.