Esri has released Service Pack 1 for ArcGIS 10. You can download it from:

Here are a few of the issues it addresses:
• The FGDC metadata standard must be maintained as an option in ArcGIS Desktop for version 10. The minimum requirement is the ability to export metadata to this format.
• Records with Null or empty string values do not export when using the Export Feature Attribute to ASCII tool
• Update ArcPress driver auto-selection to recognize Fall 2010 HP Designjet printers
• The ArcGIS metadata editor and the ESRI Metadata Translator tool were using different elements to record data quality report information. As a result, content typed in the editor would not successfully export to ISO 19139 format.
• Some 3D GP tools are not honoring negative z factor
• Some 931-SDE feature classes with Z values do not display in ArcScene
• Add detection ability to Measure Feature tool to highlight (flash) the feature clicked
• Copy/Paste a Parcel Fabric results in shapes
• When copying and pasting data that has COGO attributes, unexpected geometry may result
• ArcCatalog hides ArcGlobe Documents, or display them as Folders, if the folder they are in contains a file with no extension and the folder includes a DBF or SXD file.
• Joins not maintained after resourcing data in the Catalog > Set Data Source tool. However, relates are maintained
• Adding a standalone personal geodatabase table using the out-of-the-box ‘Add data’ tool in an ArcEngine 10 application causes an exception.
• ArcGIS 10 is not reading certain tiff images correctly.
• ArcGIS Desktop 10.0 cannot see address locators with spaces in the name stored in an ArcSDE 10 or earlier geodatabase.
• A lot more……

The service pack is for ArcGIS Desktop, Server, License Manager, ArcGIS Engine and ArcReader.