+1 for reusing the link style.
The only problem that i have with it is that it’s not clear anymore whether you want every abbreviation in the document (or paragraph – as discussed above) or whether you just intended to mark the current abbreviation.
In my opinion, the * in the common markup denotes the repetition, i.e. “every occurence found should be replaced”. Therefore, in normal writing i wouldn’t necessarily expect an asterisk to be there.
That’s what I like about the point of @mofosyne: why not add it into the link syntax? The asterisk part in the link/abbr definition would then only be used if you want to mark every occurence of the abbreviation.
I don’t know if that would ever be usefull, but one could even extend this thought to links:
You can use google to search [stuff][1]. I mean: google is your friend. Damn you, just google it!
*[google]: google.com <!-- Link on every occurence -->
*[friend]: "enemy of the enemy" <!-- Abbr -->
[1]: example.com/stuff <!-- single link -->
PS: probably there should be an option to highlight (or link) only the first occurence in a paragraph.