ARIN is telling everyone that will listen that by 2011 they will be out of IP Addresses to give out. I have already seen where they are denying some ISP's additional address space.
If you are rolling out VoIP deployments, you might want to consider rolling to an IPv6 network plan now - instead of having to re-name every endpoint.
"To stay ahead of the Internet’s explosive growth, Qwest Communications today announced it is offering public and private Internet Protocol Version 6 (IPv6) addresses to its government and business customers. Now Qwest iQ® Networking service customers can take advantage of IPv6’s built-in security measures and options, as well as a near-endless supply of IP addresses." [source]
Who else has IPv6? Look here or give me a shout.