We have not conducted any rigorous research on this but based on our empirical data it appears that there is a lot more excitement about the SQL Server 2008 release than there was for the release of SQL Server 2005. Our user base today is orders of magnitude larger than it was when SQL Server 2005 was released but proportionally we have been receiving 3 times as many inquires about support for SQL Server 2008 nowadays than we were receiving then for SQL Server 2005.
A survey conducted by SQL Server Magazine showed that about 81 percent of the participants are still on SQL Server 2000 and only about 40 percent are using SQL Server 2005. I am willing to bet that one year from now over 50% of those same people will be already using SQL Server 2008 - there are just too many cool and very useful features in SQL Server 2008 that make it really hard to pass.
All xSQL Software tools support SQL Server 2008.