The bug was recognized in July 22nd 2009. At that time Google was "working on a fix".
It's almost October, so they may not be working terribly hard.
I came across this bug when I went searching for an old post on my 3G iPod -- and discovered it was AWOL.
Update: It's not fixed in draft.blogger.com either. The dashboard does display the correct post count of 5,336. However, if you have the 'show edit' feature enabled and you're authenticated, you can browse to older posts and edit them by clicking the 'pencil' icon.
Update 9/25/09: Here's a July article from Google's official "known issues" feed.
Update 12/22/09: Still broken. Google broke radio silence to say they plan to fix this "early next year". I assume this means it will be fixed around June 30, 2010 -- about one year after Google broke the archives. A one year turnaround is pretty impressive - in a bad way.
Update 7/30/10: It's fixed! They did that very quietly.