I exported my blog from blogger and they changed it to XML.
I imported the resulting file to a test WP3.0b1 install.
This went well. Careful checking showed that it appears all my stuff came across.
Some users did test comments and I created some test pages and posts.
All was working fine.
I upgraded to WP3.0b2 and this appeared to go well.
Posts: 985 published
Posts: 423 drafts
Life is good in WP land.
I exported all of my blog from WP3.0b2 to an XML file#2.
I created another WP3.0b2 install on another server.
I imported the XML file#2 to my second WP3.0b2 install.
Posts: 906 published
Posts: 317 drafts
Life is not so good in WP Land. A lot of posts and comments were lost. Since the import from blogger worked fine I suspect that the problem is on the export side. But I did change from 3.0b1 to 3.0b2 between those imports so no guarantees.
Appears to be a bug in import.
These are test sites. Let me know if I you need more details.