Still... nothing like finding out for yourself first-hand. Many digicams have anti-aliasing filters that block IR but some block more than others. So it doesn't mean that if there's an anti-aliasing filter, then IR photography is impossible. Case in point is the Canon 10D/20D which has a very strong IR-blocking anti-aliasing filter but still could take IR pics.
To test it for yourself, just point and fire any IR remote control (for your TV, VCR, DVD player, etc) at the camera and see whether the LCD display of your camera shows a blinking/flashing image of the LED of the remote control. If it shows, then your camera is sensitive to IR and there is a very strong chance that it can take IR photos when fitted with an IR filter.
I did check the FZ20 - it doesn't see anything, while my Kyocera Finecam L3 see a very bright light. However you can either buy a weak filter or make one yourself following the instructions found here : http://www.amasci.com/amateur/irgoggl.html
The only difference is that you need a filter holder like the cokin one and will cut square pieces out of it. You can find those filter on ebay too from JayPlayer. I will recive the gels soon so i will be able to tell whether they are any good. The advantge of using them is that is very cheap and pretty weak, so most likely to let some light pass.