Openbravo the open source ERP software has just released the latest version of their POS (Point Of Sale) software. Openbravo POS was a recent acquisition of the open source EPOS system formerly known as Tina POS and Libre POS.
Openbravo POS can be integrated with Openbravo POS for complete solutions for retail including restaurants, grocery stores, specialised retailers and department stores.
Openbravo POS is designed for touch screen tills and supports a wide list of standard POS hardware

Screens are designed for different environments for example restaurant booking:

and restaurant seating plans:

Summary
Current Version
2.2 (released August 2008)
Platform
Installation – Windows, Linux, MAC OSX
Database Database independent, using the standard JDBC interface. Openbravo POS currently supports Oracle, PostgreSQL, MySQL and HSQLDB. Adding a new database engine is very easy, with little modifications required in the code base
License
GNU General Public License,
Proprietary ERP Competitors
SAP, Oracle, Microsoft Dynamics
Useful Links
Site http://www.openbravo.com/product/pos/
Wiki http://wiki.openbravo.com/wiki/
Blog http://adrianrcblog.blogspot.com/