Why you can just head on down the Cow path aways and mosey on over to
http://forums.creativecow.net/telestreamwirecast
It's cross platform (Mac/Windows).
Consider it a full production switcher and it'll run right from your laptop.
Make sure it's a fast laptop. I'm using MacBookPro CoreDuo 2.4GHz
Firewire port can take one DV camera.
Express firewire adaptor gives you a 2nd camera.
This laptop has built in WebCam and mic but you can certainly toss on more with the USB bus.
Mac version will stream Quicktime or Flash with H.264 codec.
Windows version adds Windows Media streaming as well.
You'll want at least 500kbps-768kbps up at least but you can get by with less if you don't mind a lower quality speed.
Test your upload speed here
http://www.speedtest.net/index.php
pick server targeting your server location.
If you really want down and dirty (no budget) you can use Quicktime Broadcaster (just camera and mic basically) to stream to a Quicktime or Darwin Streaming Server.
Unfortunately Adobe has not made Flash Media Encoder on the Mac side but it certainly works well if you're on a Windows computer and you can stream using either VP6 or H.264 to a Flash Streaming Server.
If you don't have a CDN or your own streaming server there's Livestream (was Mogulus until today)
http://www.livestream.com/
and
http://www.ustream.tv/
which you can setup free accounts with (with overlay ads but viewers can click them away periodically).
The both have "Pro" versions (LivestreamPro starts at $350/mo) (Watershed has pay as you go or starts at $49/mo).
That's a basic overview but I can give you details if you describe where your headed with this.
If you head in the direction of Wirecast as production switcher streaming software head over to that forum as other Wirecasters may chime in with additional suggestions.
