I'm not going to blab about the speculation, or how Microsoft seems to like making their promised deadlines by the skin of their teeth. I'm too busy preparing how we're going to deploy and test SP2 on all of our SQL Server 2008 instances. So without any delay, here are the downloads / fix information:
Download Details: Microsoft SQL Server 2008 Service Pack 2
KB #2285068 : List of the bugs that are fixed in SQL Server 2008 Service Pack 2
As we've seen before, the release has been quietly posted to the downloads site and knowledge base with little fanfare, and there is not yet a post on the SQL Server Release Services blog. But I'm sure you'll hear more about it soon.
Note that the Service Pack only includes the fixes that were in SP1 CU 1 through 8. So if you have already applied CU9 or CU10, I would hold off on deploying the service pack for now, especially if you are relying on any of the fixes in either of those CUs - because there is a chance that you will lose them.
The service pack will patch any existing SQL Server 2008 instances (and client tools) on your machine, including Express instances (I seem to remember that you used to have to patch Express instances separately, with the whole Express setup program). Note that you can't patch client tools with a SQL Server 2008 Service Pack if you already have SQL Server 2008 R2 tools installed - this just means that the Shared Tools checkbox will be unavailable.
I know that some of you like to hear about the build numbers more than anything else. This service pack will move your build number to 10.0.4000:

Fellow SQL Server MVP Denis Gobo (blog | twitter) spoke about some of the changes introduced with Service Pack 2.
EDIT: And here are the announcements from the SQL Server Team Blog and SQL Server Release Services blog.