This is a post which will make some of you smile, but only if you are using Websense v7. This solution will block igoogle in all it's forms.
#1 Remove all present recategorization entries for igoogle.
#2 In Websense Manager, click on "Recategorize a URL" from the tasks pane on the right hand side of the page.
#3 Select a previously created, custom-blocked category or add a new one, select it, then click "add".
#4 Click on "Advanced" to show the "Regular Expressions" dialog then click on "Add Expression".
#5 Add these two entries:
google\.[a-z]*.[/]ig
google\.[a-z]*\.[a-z]*.[/]ig
#6 Save your changes, then check if the policy applied to your users has the custom category containing this entry set to "blocked".
This works for me, hope it works for you too.