Haven't been able to find this topic covered so I'm posting it as information.
A desktop shortcut to open multiple tabs in Firefox can be created using the "pipe" character to separate the different URLs of interest (e.g., http://www.cnn.com/
I can, of course, go to "Bookmarks" to launch a multitab entry but I have so many "Bookmarks" that I find it much quicker to use a shortcut to the one or two key multitab references that I use most often.
One issue I've encountered so far is that launching a second, multitab shortcut opens in the most recently opened browser window rather than a new window. Firefox only opens one new tab for the first URL, however, and drops the other URLs. It seems that the second shortcut should initiate a completely new instance. If anyone knows why it doesn't work that way, please advise.
BTW, I haven't tried this with IE.