If we're porting security tools, I'd rather see something like Snort, but a simple firewall could always be great too.

(Especially for those on T-Mobile USA's IPv6 trial. Because I'm pretty sure some enterprising hackers would love to get on that soon enough. There aren't enough mobile devices with unique IPs out there yet, but as IPv6 increases in abundance, I'm sure it'll become an issue. Of course, we could trust the phone service providers to filter our traffic for us... or we could realize how bad of an idea that is now, and save ourselves the trouble.)