Maan I've missed posting a bunch of things for my future self.
Here are a couple.
When using geda's pcb layout, if you set the pad clearance on parts to zero, you can do honest copper pours for ultra-high-power or heat-dissipation situations. Tricky because the copper won't separate from unintended pads, so you need to know what you're doing when you pour the copper. Best done by running all the traces, then running the copper over them, then deleting them, so you know you're not inadvertently shorting.

Gnome3 has very irritating sliders on all the windows. A suggestion for disabling these:
# echo export LIBOVERLAY_SCROLLBAR=0 > /etc/X11/Xsession.d/80overlayscrollbars

I've installed Ubuntu 10-04LTS on a new machine to get used to it, since it's what the newest EMC2 CNC controller is based upon. Under system>preferences>appearance you can change the theme so you have the window controls in the upper-right-hand corner rather than the upper-left-hand, as it comes stock.
My stock installation didn't have f-spot working correctly: when it started it died invisibly and when I kicked it off from the command line I got a big pile of errors:
Unhandled Exception: Mono.Data.SqliteClient.SqliteSyntaxException: no such table: tags
at Mono.Data.SqliteClient.SqliteCommand.GetNextStatement (IntPtr pzStart, System.IntPtr& pzTail, System.IntPtr& pStmt) [0x00000]
at Mono.Data.SqliteClient.SqliteCommand.ExecuteReader (CommandBehavior behavior, Boolean want_results, System.Int32& rows_affected) [0x00000]
at Mono.Data.SqliteClient.SqliteCommand.ExecuteNonQuery () [0x00000]
at Banshee.Database.QueuedSqliteCommand.Execute () [0x00000]

I went to /home/john/.config/f-spot and removed photo-db and then f-spot worked as it was supposed to.

I hope it is glaringly obvious that this is only an acceptable repair for a brand-new installation and you Do. Not. Want. To. Do. This. if you already have photos in an existing installation.

gschem and pcb work beautifully. The MSP430 jtag programmer and debugger work beautifully. Dual-screen worked well out of the box, running what I believe to be stock xorg graphics drivers. (It's running on an nvidia card, and generally those play well.) Digikam is broken: it correctly detects a camera but claims it can't establish a connection. Unfortunately, showFoto and digikam are strongly interlinked so I get to keep a broken digikam if I want showFoto, and showFoto is a much quicker way to crop/edit pictures than gimp. Imagemagick is amazing, I grant you, but if I'm in a hurry and only have to do one photo, showFoto is a quick way to process it.

Inkscape works beautifully, including the G-code plugin, allowing me to convert any artwork Inkscape can use directly into stuff that loads onto a milling machine. Pure unmitigated awesome.

I'm still not convinced that sudo is a great idea. I think it gets in the way a lot more than a standard unix user/root division. But the experience is growing on me.

The automatic-update-of-kernels is neato. The resulting deluge of entries in grub is *not* neato.