I saw this post from Rick Strahl about IP6 Addresses in Vista breaking some code, and it immediately made sense that we're probably going to feel some pain on the db site. While all it may take is altering a column on our side (which increases space usage of course) but it could also result in proc changes, and even application code depending on how things were typed. As much as I read I tend to not focus on the networking side of things very much because I've either had a network admin, or just opted to do without one because we only had a couple servers. Not often that changes on their side affect us, but this is one.
I'd suggest checking tables for storage of IP addresses, applications that process server logs into tables, and application code/procs that log the users IP address (obviously common in web apps).