There's a simple solution to the unmounting trouble: when the Quicksilver file is downloaded you'll notice it is called QS.3815.dmg.bz2.
Rename it by removing ".bz2" and you'll be able to unmount the diskimage.
Great app by the way, though I don't think I'll use it much...
Quicksilver
launcher & data manipulator
Version: 1.0b54
Installing Quicksilver
Feedback Type: Troubleshooting Report
Contributed by: nout72 Friday, July 18 2008 @ 02:30 PM PDT
Product Platform: MacOSX
Used Product For: Less than a month
System Info:
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