All upgrades to SQL Anywhere can be found on sybase.com. Under the Support menu at the top, click "EBFs/Maintenance" and then click "SQL Anywhere". For older versions, you may have to adjust the dropdown at the top, which defaults to "in the last 6 months".
However, the latest version of SQL Anywhere 11.x is 11.0.1.2825 (as of July 24, 2012). There has never been a version 11.0.1.48xx.
Since this is not a programming question, it's not really appropriate for StackOverflow. You may want to try asking SQL Anywhere questions at http://sqlanywhere-forum.sap.com/.
Disclaimer: I work for Sybase in SQL Anywhere engineering.