More coming next week in editorials and already a note on the site, but support for both SQL Server 2000 SP3a and SQL Server 2005 RTM ends on Tuesday.
What does this mean? Well when support ends, at least mainstream support, you can't make free calls on it. So if you install a new server (ss2k5) on Monday, have an issue Wed, even if you're under some plan or warranty, you won't get support from MS until you apply at least SP1. I'm not even sure you can pay for extended support anymore for this service pack level like you can for the products themselves when they pass out of the mainstream support lifecycle.
For many people, this isn't a big deal. Usually within 6 months or so people are applying the Service Packs to their machines. However for some people, especially those that use smaller vendors, they may be significantly behind in waiting for their applications to get certified. So put pressure on vendors to certify the latest service packs ASAP so you can upgrade.
The other thing I'd mention is that Microsoft needs to stop the enhancements in service packs. I know it's a cool way to slip in a few features, but changing behavior, other than bug fixing, makes it hard to ceritfy new applications and increases the risk of issues. Just patch bugs and give us a semi-annual or annual rollup of new features.