Nope, it's the starter.
I had it happen again this weekend - couldn't start so I hooked up the jumper cables to my xB... Still wouldn't crank! So it has to be either the starter or solenoid. Alas.
I think I am draining the battery a bit too on the drives, so I picked up a battery charger from Harbor Freight. I'll plug it in once a week to top it up.
While I was at Harbor Freight, I also picked up a cheap timing light and finally timed up the ignition properly (It's been off for years, apparently by more than 5 degrees...)
Funny story. I started the engine and idled it up to operating temperature, attached the timing light and couldn't see the marks (covered by dirt/corrosion), so I shut the engine off to see if I could find them (nope).
Tried to push-start it down the driveway... AND FAILED!
The car was stuck, half-way sticking out into the road (quiet road thankfully). So I grabbed a chain from the garage and fired up the ugly truckling ('86 Toyota Pickup) to tow it back up the driveway...
I tried to push start again... AND FAILED AGAIN!
Back on with the chain to drag the thing back up the driveway...
Push start worked this time, and I got it back up the driveway under power... ONLY TO SHUT OFF THE ENGINE!! D'OH!!
Push start once more and left it running this time...
I hope the neighbors weren't watching all this.
I touched a wrench to the spinning crankshaft pulley to clean it and I could then see the marks. It took me well over an hour to do the timing, but the test drive proved it was worth it. A bit more acceleration/power and a happier engine I'm sure.