Since I probably won't be the "first post!" winner, I'll go over the highlights of what you're getting (some of which are not mentioned in the What's New document). Before I do that I'll post the links:
SQL Server 2005 SP2
KB 921896: A list of the bugs that are fixed in SQL Server 2005 Service Pack 2
What's New Document
February 2007 Books Online
Jasper collected more links than I did
Highlights
- User-defined reports in Management Studio
- New VARDECIMAL storage type
- Various fixes to maintenance plans, including multiple schedules, a maintenance cleanup task, and they no longer require Integration Services;
- Better backup/attach/restore dialog features;
- Better scripting options;
- Context menu for views is more clear (added Edit and Design, removed Modify);
- Better error reporting for Database Mail configuration problems;
- More reliable copy database wizard with better logging;
- Better permissions viewing experience;
- Logon triggers, and a CCC option in sp_configure;
- Object Explorer Details tab replaces Summary Tab;
- New SMO methods Table.CheckIdentityValue() and Column.AddDefaultConstraint();
- Reporting Services can now be integrated with SharePoint Services 3.0 or Office 2007 SharePoint Server;
- Much of the color coding omissions have been cleaned up;
- Plan cache improvements;
- New table-valued function sys.dm_exec_text_query_plan;
- Better layout in graphical showplans;
- OBJECT_NAME() now accepts an optional DB_ID parameter;
- New function OBJECT_SCHEMA_NAME() allows you to get the schema for an object by name, without having to join multiple catalog views;
- New procedure sp_refreshsqlmodule
- Disk Usage report has been overhauled, and in general, in-built reports perform better; and,
- Vista support -- allegedly. I was unable to upgrade my client tools on this machine.