I don't see why not. The question here is whether you think it will benefit your users or not. Personally speaking, I find it a tad bit annoying whenever I'm brought to the mobile version of a website, even though I'm using a desktop computer. Do note that you should create some sort of URL fragment that can be used whenever you do not want to be redirected (this GET variable should set a cookie that prevents redirects in the future. Useful for debugging and for allowing desktop users to avail of your mobile site).
Alternatively, you could make sure that your mobile site is responsive and that it provides an option for the user to return to the desktop version of your site. If you look at Wikipedia's mobile site, you'll see that the page width expands and that there is a link to the desktop version in the footer.
PS: Redirecting based on User Agents isn't foolproof and you might run the risk of constantly redirecting mobile users to your desktop website. Make sure that you're OK with this before you implement such a redirect.