In SQL 2005, you could use the options -C 65001 and CODEPAGE = 65001 to
load UTF-8 files with BCP and BULK INSERT respectively. In SQL 2008 this fails,
and the error message from BCP gives a clear hint that this is intentional.
I found https://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=321839
which may give an explanation for this drastic step.
However, I can find no documentation about this in Books Online, and neither can I recall
having seen this in release notes or a Readme. It appears that this change was introduced in RC0.
While the bug in 321839 may not have passed the bar to be fixed in RTM, it seems quite
astonishing to defer the bug all to SQL 11 in hope that you will have native UTF-8 support
in the engine then. After all, this is was existing functionality in SQL 2005, with or without the bug.