Looks like Mathematica 9 is released. I haven’t yet had a chance to take a look. Glancing through their release notes, a few interesting things I hope to try at some point are

– Signal Processing, which for some reason was fairly week on Mathematics till date, compared to Matlab for instance.
-The (random and social) network analysis tool is something I hope they made powerful.
-Integration with R.
-Time series, random process analysis new features and may be more.