Autodesk have released Service Pack 1 for the Inventor 2009 series of products.
The above link points to both the X32 (31MB) and X64 (68MB) versions of SP1. Our initial findings internally are that Inventor opens a little quicker and does seem more stable.
We have also received an link via the Autodesk Subscription System to some Productivity Tools only currently available to those on subscription. These are for Part Modelling, Drawing Management and Assembly Design. Those users on subscription can download the tools now – Unfortunately, those not on subscription will have to wait until the release of Inventor 2010 next year.