A bad solenoid is certainly possible, but I've only replaced one in 16 years, so I'm playing the odds here.

If you jump the solenoid, use a jumper cable (on the large threaded posts). If the solenoid is the problem, the full current to the starter will flow through it and light up a "regular" wire.
Make sure it is in park before you do this. If it is in gear, it will start and drive away from or over you.
Ask me how I know

If you get nowhere with this a 10-15 dollar meter from radioshack will go a long way.

Craig