If you have ever come across an extension that you know has a newer version but magento pretends it is not there eg
./mage upgrade http://connect20.magentocommerce.com/community/ m2epro_ebay_magento
Checking dependencies of packages
Already installed: community/m2epro_ebay_magento 6.2.2, skipping
Enter…
./mage clear-cache
This will force magento to look with new fresh eyes and magically upgrade your extension for you
./mage upgrade http://connect20.magentocommerce.com/community/ m2epro_ebay_magento
Checking dependencies of packages
Starting to download m2epro_ebay_magento-6.2.4.2.tgz …
…done: 2,360,256 bytes
Installing package community/m2epro_ebay_magento 6.2.4.2
Package community/m2epro_ebay_magento 6.2.4.2 installed successfully
Package upgraded: community/m2epro_ebay_magento 6.2.4.2