Since I fell into this old question and then found that it is now possible (maybe this css option wasn't available then), I just want to add an update on how it can be done:
<a href="[yourlink]" target="_blank" style="target-new: tab;">Google</a>
Here are the options for the target-new style:
target-new: window | tab | none
Didn't test the none option, maybe it uses the default browser setting.
I confirmed this for Firefox and IE7-9.