Rollup 7 breaking workflow publishing?

I can't be certain, but I think Update Rollup 7 for CRM is breaking my ability to publish workflows that contain email steps. So far I have encountered this twice, for two different customers, and it is really annoying. Fortunately, I have found the solution!

The error that appears in the trace file (if you do a trace while attempting to publish the workflow) comes up something like this:

>Crm Exception: Message: Workflow compilation failed:
WF1399: Activity 'SendEmailStep5_policy' validation failed: Property "RuleSetReference" has an invalid value. Rule set is invalid. Rule "main" validation failed. Type System.Globalization.CultureInfo is not marked as authorized in the application configuration file.
WF1399: Activity 'SendEmailStep7_policy' validation failed: Property "RuleSetReference" has an invalid value. Rule set is invalid. Rule "main" validation failed. Type System.Globalization.CultureInfo is not marked as authorized in the application configuration file., ErrorCode: -2147201023

The error actually provides a clue as to the problem, but it wasn't entirely obvious to me. There is a line missing from the web.config file which, when added back, resolves the issue. The line is:

<authorizedtype assembly="mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" namespace="System.Globalization" typename="CultureInfo" authorized="True"></authorizedtype>

I've just been adding it to the end of the list of authorized types for mscorlib. You don't even have to restart IIS - it just begins working as soon as you save the file.

UPDATE: I had to put in the HTML escape characters for the brackets to show up in here - my apologies for the line not appearing before!