Okay Chris...here's what happened after we downloaded the sample...
1. Register the dll.
We accomplished this with no issues.
2. Open the 'Component Category Manager' by running categories.exe from your installations Bin directory.
This is located at C:\ProgramFiles\ArcGIS\Bin\Categories. Done without issue.
3. Select the 'Text Background Property Pages' component category and use the 'Add Object' button to add the TextCallouts.PropertyPage.
We did this with no issues.
4. Select the 'Text Backgrounds' component category and use the 'Add Object' button to add the TextCallouts.CircleCallout.
Again, no issues.
5. Open ArcMap.
Yep...no problem.
6. Add a text element onto your map.
Done.
7. Right-click on the selected element and select 'Properties' from the context menu.
At 10 this is known as 'Attributes', not 'Properties' for text elements.
8. Select 'Change Symbol'.
Done.
9. Select 'Properties'.
At 10 this is 'Edit Symbol...'
11. Select the 'Advanced Text' tab.
Done.
12. Click on 'Text Background', then select its related 'Properties' button.
Done.
13. In 'Type', select 'Circle Line Callout'.
The new type does not appear in the list.
Can you or someone there try to run this to see if you experience the same issue with 10?
Sorry to be such a pain...but again, this is a critical label that we need in order to effectively complete our workflow. Strange that we have all these obscure and rarely used CAD symbols yet this one is pretty commonly used and is nowhere to be found?!