One of the known issues with SharePoint 2007 is the inability/quirkiness of filtering a view based on the status of a workflow field. While this is a pain, there is an easy workaround. Simply create the filter and tell it to look for the integer representation of the status value you are looking for, like this:

This will create a filter that returns all "Approved" items. The codes are:
| | Status | Value | |
| | Not Started | 0 | |
| | Failed on Start | 1 | |
| | In Progress | 2 | |
| | Error Occurred | 3 | |
| | Canceled | 4 | |
| | Completed | 5 | |
| | Failed on Start (retrying) | 6 | |
| | Error Occurred (retrying) | 7 | |
| | Canceled | 15 | * This is defined but I don't think this value is used |
| | Approved | 16 | |
| | Rejected | 17 | |
12/19/2007 Update: Filled in list of values using the actual values found in the field definition itself.
5/28/2008 Update: Hit by a flash of the blindingly obvious. If you put the status fields on a view, then view that in the Datasheet mode, it shows you the integer values. I don't know why I hadn't seen this before ....
