Hmm ... I have one-click access to all the open windows, via the contextual menu items and the right mouse button (or use control-click). Pops up a list of the app's open windows, and off I go ;-).
If one ever does get created, I really hope it's either third party (so I can not install it) or optional (so I can turn it off). There's nothing I hate more than using my Win98 box for a few hours, then looking down at the task bar and seeing informative labels on microscopic boxes like "My C...", "C:\Dat...", "D:\Gam...", "Novel...", "Microso...", "Microso...", etc. Yea, if you hover you get the whole label, but what a pain. WinXP finally fixes this by consolidating open windows in one task bar entry per app.
-rob.