Ok, I'm a bit of an ID10T at times.
I've talked about this for months, especially trying to push SP3 for SQL Server 2005, but when the date came I missed it. I could blame it on a busy life and a wife that's been gone 7 of the last 12 days, but the truth is I blew it.
Support for SQL Server 2000, both Service Pack 3 and 4, ended yesterday, April 8. If you don't have a maintenance contract, or don't buy one, you're not getting anything fixed. Even if you have an issue, there are no guarentees, but at this point you cannot report a bug or issue and hope it will get fixed.
So, if you're still on SQL Server 2000, and many of you are, then you are without support right now.
My guess is that most SQL Server 2000 systems are fairly stable. If they're not, and you've got an open case, I assume Microsoft will keep working on it, but I'm not sure. I'll try to find that out when I'm up in Redmond next week.
I acutally don't think it's that big a deal to run without support, providing you've been running in a stable mode for awhile. There's always the chance you'll hit some new bug with enhancements or changes to your code, but it's not that likely. If you haven't upgraded yet, I'm not sure I'd be in a panic at this time to upgrade. I'd be thinking about it and perhaps planning/budgeting for a move to 2005 or 2008 sometime in the next year, but chances are you are fine for now.
Remember there are still people out there on SQL Server 7 and even SQL Server 6.5 that haven't had support for a very long time and are doing just fine.