The direct link to the version 10.0 Service Pack 4 page is:
Note: Please see this Hot Topic post about an issue with SmartList Builder after SP4.
Note: Please see this Hot Topic post about issues with Extender after SP4.
Service Pack pages for all current versions can been found on the Developer Articles & Links page.
Have a look at these blog posts for more information:
Note: Please do not post questions about technical issues in the comments, you would be best to post on the newsgroups (links in right hand panel) or create a support incident.
26-Aug-2009: Added additional Blog links.
31-Aug-2009: Added link to Hot Topic SmartList Builder blog post.
25-Sep-2009: Added link to Hot Topic Extender blog post.