Really quite easily you can use the multisite functionality to change the entry point.
Copy the index.php and .htaccess file to the root or folder you want the store entry to be in such as http://www.example.com instead of http://www.example.com/magento
Alter index.php so that the path to the app/Mage.php is instead magento/app/Mage.php like so:
$mageFilename = 'app/Mage.php';
$mageFilename = 'magento/app/Mage.php';
Then you will have 2 entry points for your default store. If you don’t want an entry point in magento/ any longer, you can either just rename or delete the index, or write a new index.php to redirect to the proper entry point if you know how to do that.
You will then need to change the web settings in the admin to reflect the new base domain and links. (System->Configuration->Web)
You can use this same technique to add multiple store fronts at subdomains or other domains hosted on your account as well. I have one install just for fun that runs through 30 some odd subdomains, each as it’s own seperate store.
For each install I created a Website/Store/StoreView and gave them their own Web Settings in the Configuration so that on each specific subdomain or domain the correct urls are added for the links and yet all the skin, media and js is drawn from the single original install.