Hopefully many of you have now upgraded to the Silverlight 1.0 RC (or 1.1 Alpha Refresh bits). Just as a reminder, the beta release is due to expire tomorrow (August 1st). If you have the beta release installed on your machine, you'll see a dialog box appear that reminds you that the release has expired. The workaround is of course to update to the RC bits.
This shouldn't be a surprise (!), since near the start of the beta EULA, there is the following clause:
2. TIME-SENSITIVE SOFTWARE. The software will stop running on August 1, 2007. You may not be able to access data used with the software when it stops running.
The 1.0 RC SDK includes details on breaking changes that will help you to port code forward; if you're using Silverlight Streaming to host your application, Tim Heuer has a great post that explains the changes you need to make.
To answer the obvious question, Silverlight 1.0 RC expires on November 1st, 2007. By that stage, we'll have auto-upgraded the runtime to the final release - and unlike the beta -> RC migration, this will be seamless since there are no breaking changes between the RC and the final versions.