Is there a way to hide the \"XHR finished loading\" messages in the console?
Yes, open the contextmenu in the console, and remove the check at Log XMLHttpRequests.
You can still inspect the network traffic at the Network tab.
There is some workaround posted in chromium issue tracker http://code.google.com/p/chromium/issues/detail?id=15472
Which version of chrome you are using? In my console there is checkbox to enable or diable log XMLHTTPRequests I am using 17.0.963.79