A new gadget for Google Desktop called Google Media Server allows you to take content found on your computer or online Google services like YouTube and Picasa Web Albums, and shares it with UPnP compatible devices like the PS3. Unfortunately, as explained in the discussion group, Google Media Server does not work with Xbox -- they integrating is technically possible, but their legal department won't let them do it.
Initial reviews aren't spectacular, but the software is beta, and I think it's a good start.
If you want to give it a try, install the Gadget on your Windows machine (from what I can tell, it only works on Windows) then click on the options button. You can then select which of these devices have access to the media on your computer. For example, if you have a PS3, you will be able to select it here.
In order to protect your privacy, Google Media Server requires that you authorize which devices are allowed access. This can be configured by clicking the "Options" button on the Gadget interface, and then selecting "Devices" from the left hand column. Check the devices to authorize and click the "Save" button. You can now access media on these devices using Google Media Server.
What do you think of Google Media Server? Should it have been a more polished product before launch?