Bit of a plug for Quest software here but their tool to migrate SharePoint subsite’s, site collections and content has now been fully released. This post is slightly late though as the official release was on the 6th August 2009!
The official page is here –
And this blog post by the quest team talks about some of the features –
Their previous version of the software was called the ‘Reorganization Wizard’, we ran into problems moving subsites around within our farm and this software came to the rescue.
I would urge you all to check it out as its packed full of useful functionality.