Question: I know target="\_blank" is supposed to make the thing open in a new window, and for some browsers, like FF3, it will actually make it open in a new tab. Is there a way to exercise more control over this behavior as a developer?

Answer: 
According to <https://developer.mozilla.org/En/Window.open>, """
**How do I open a referenced resource of a link in a new tab? or in a specific tab?**

Currently, you can not. Only the user can set his advanced preferences to do that. K-meleon 1.1, a Mozilla-based browser, gives complete control and power to the user regarding how links are opened. Some advanced extensions also give Mozilla and Firefox a lot of power over how referenced resources are loaded. 

In a few years, the target property of the CSS3 hyperlink module may be implemented (if CSS3 Hyperlink module as it is right now is approved). And even if and when this happens, you can expect developers of browsers with tab-browsing to give the user entire veto power and full control over how links can open web pages. How to open a link should always be entirely under the control of the user. 
"""
Whether something targeted to "\_blank" opens to a new tab or window is a browser/user specific option settable in most new tab supported browsers. There is no way to target a tab yet.