Not quite wget, but the Linode API does let you update your DNS resources, so it shouldnt be too hard to script an update process for your home machine.
Alternatively, for maximum flexibility one thing you could consider would be hosting the DNS zone master yourself on your Linode, and then have the Linode DNS configuration slave off of your Linode. This gives you complete control over your zone and you can implement whatever dynamic update methods or features you want yourself, while retaining the redundancy and availability of the the Linode servers.
-- David