Marshall - 1:01 pm on Mar 13, 2012 (gmt 0)
Everything I have read (and implemented) on mobile designs has a max-width of 480px. And as you pointed out, people will just zoom if necessary. However, screen width is not the first thing to consider/worry about in mobile designs. Two more important issues is compatibility with as many mobile platforms as possible (a real nightmare) and being considerate to your users by limiting data transfer to what they need and not include superfluous information. You have to think about download speed and bandwidth usage (they may be paying for bandwidth usage). The other important consideration is making the link areas large enough so people with large fingers can easily use a touch screen. I41px high seems to be a comfortable setting.
But back to your OP, making it dynamic up to 750px, you might as well not even bother making a special mobile version, IMHO.