Google Apps users now have the option of turning on "The new compose in Gmail".
Note that you've always been able to Shift-Mouse Click the Compose button to open your new message in a separate web browser window. You can also click the small black up arrow on the right hand side of the "To:" field to open in a window after you've started composing.
We are bringing this to your attention because the new compose button is missing lab features like Canned Responses and doesn't appear as a separate window on your Windows taskbar making it harder to find when it is embedded in your main email tab.
Certainly try it out. You can always switch back to the prior compose interface from the arrowhead menu at the bottom right corner of the new compose feature.