IBM DB2 Express-C is free to download, free to develop, deploy, and distribute
Now there is an express version of DB2 for community which is a free downloadable database named DB2 Express-C. DB2 Express-C is a version of DB2 Universal Database Express Edition (DB2 Express) for community use. You can use DB2 Express-C for developing applications including C/C++, Java, .NET, PHP and more.
It supports up to maximum processors of 2 and a maximum addressable memory of 4GB.
Some of the extented features that are not included in DB2 Express-C edition are Warehouse Management Tools and Servers and Replication capabilities.
If you are new to DB2 you can get a review by attending the 7 minutes entry at How do I get started with IBM DB2 Express-C? web pages.
Also you can order a free demo DVD, The DB2 Express Discovery Kit from IBM DB2 9 Discovery Kit order page.
The free DVD includes the DB2 Express-C Edition, whitepapers, case studies, webcasts as well as product demos.
You can find the download link for DB2 Express-C Edition at IBM DB2 Express-C download page
There also exists developer tools for use of developers like DB2 Viper Developer Workbench and DB2 Viper Runtime Client. The DB2 Viper Runtime Client is the connection application for your data driven applications. And DB2 Viper Developer Workbench is a development environment for building data driven applications with DB2 Viper. You can use it to create, edit, debug, test, and deploy DB2 stored procedures and user defined functions, along with SQL, SQLJ and Xquery APIs.