It seems it was almost yesterday when SQL Server 2008 went RTM. And now, less than 60 days after 2008 was released, Microsoft has released Cumulative Update Package 1, which includes 78 hot fixes. You can see the entire list here.
As is the general rule of thumb, it is not recommended that you install hot fixes unless you know you really need them to fix a specific problem you are having. On the other hand, this requires that you take the time to review all 78 of the hot fixes to see if they are applicable to you. If one or more of the hot fixes are applicable to you, then you will probably want to install this update (after considerable testing, of course) on any SQL Server 2008 servers you have in production.
On the other hand, if you don't have any of the problems covered by the hot fixes in this update, then save your time and skip this update, and wait for the first service pack, which should be released in late 2008 or early 2009.