A widely discussed topic online is the fact that we've almost run out of unique identification numbers which are used to identify addresses on the web.
Rather like when British car number plates switched from X000XXX format to XX00XXX format, the same thing is required online, except the problem expected is that ISPs (Internet Service Providers), don't all seem geared-up for the change.
According to The Register, 97% of IPv4 IP Addresses are now in use, and are estimated to be completely used-up by some time in spring 2011.
IPv6 is the new standard, designed to account for the growing demand for IP addresses, so time will tell if this is a genuine cause for concern, or scaremongering on a par with the Millennium Bug!
The Register sums it up pretty well, here.