+2  A: 

To do this just use a comma (a.k.a. the multiple selector), this works for any number of selectors.

$("#Tags, #Tags2").tagSuggest({ 
  separator: ", ", 
  tagContainer: 'div', 
  tags: ["tag1","tag2"] }); 
});

There's a list of all selectors here and a good start-up tutorial you should check out here.

There's another approach, not needed for your example really, but if you had a lot of elements you wanted to match, or an unknown number, etc...then use a class, like this:

<div class="tags"></div>

And you can select all elements that have that class using the .class selector, like this:

$(".tags").tagSuggest({ 
  separator: ", ", 
  tagContainer: 'div', 
  tags: ["tag1","tag2"] }); 
});
Nick Craver
Superb, thanks for the detailed explanation. Both methods are ideal!
Ben