I use this to death:

open .

to open the folder I'm in in Finder. Did this go away in 10.6? I can't use "open" to have Finder open any folder it would seem:

LSOpenURLsWithRole() failed with error -600 for the file /Volumes/Flash2/Files/

I tried it on my iMac and MacBook Air both running 10.6.2 and it worked perfectly.

That same error is mentioned in this thread.

Are you running Fusion 2.0 (or perhaps some other Snowy-incompatible software program)?

[idunno, no 10.6 here until after "12.25" ]

Or maybe trying to open files remotely?

no, no, and no. But I've only seen it happen on one machine here so maybe it's just that machine that's got issues.