This sound file with pictures was created in Garageband. To create a podcast in Garageband select NEW from the file menu and then "New Podcast Episode"

Once created Export Podcast to Disk from the SHARE menu (to the desktop or where ever) - it will save as an m4a (whatever that is).
Now open WikiSpaces and select "Insert Images and Files".

Once inserted into your wikispace you will probably need to resize it - this one came in VERY small but was easily resized by just dragging the corner handles.

Obviously this is not a TRUE podcast as you don't have the option to Subscribe to it but ... if you have Quicktime Pro you can download it.
This is a Windows Movie Maker file - I dropped the
pictures into Movie Maker and then recorded my voice and added the oh so cool music in acid, rendered as mp3,
added it to the movie and uploaded it as a file.
It works fine - again you have to resize it to suit but I can't seem to download a copy.
Still it would be a great way for kids to show their work etc wouldn't it?

OK OK it shows and works on my Windows 'puta but NOT on my Mac.
Just another problem to solve eh?

What about POWERPOINT? (I hear you cry) OK here's a powerpoint - an old one but I added some music rather than words and set the timing
You can download it to your desktop or view it but not on this screen - still, it does allow you to share ppts.