I opened a SPARCstation IPC to find this:

The main caps had leaked so bad that the goop dripped onto the motherboard:

Now, I know capacitor leakage can cause a lot of damage, and that SPARCstation IPCs seem to be more prone to leaking main caps than other Sun machines (see writeup here), but this made a real mess! Inside, electrolyte goop is literally pooled on the ends of the main filter caps:

I guess it's fortunate that the power supply in the IPC is mounted as it is: upside-down when the case is closed and sitting normally. The goop didn't spend too much time on the power supply circuit board, instead dripping down and attacking the plating on the power supply cage. That probably reduced its corrosiveness and limited the damage to the motherboard. After a good scrubbing with hot soapy water and a recap of the power supply, this machine is fully functional again!

Do check the caps in your machines, especially if you have something that's known to leak!