First question, although your experience is with SQL Server 2005, what have you done recently to ensure your skills will work with SQL Server 2008? Let me also ask another question, do you have SQL Server 2008 or SQL Server 2008 R2 installed at home and if so have you been learning the differences?
What these two questions are getting at is that if you get a chance to talk to the recruiter, demonstrate that you are competent in the newer version(s) of SQL Server. If you can show that you know the changes made and can work with them, I would hope that would help the recruiter understand that even without direct, paid experience with SQL Server 2008, you are keeping yourself current with the newer technologies.
If that still doesn't work, you may need to find another recruiter. One thing I have found in the past few months is that many companies contact multiple recruiting firms for the same position. I had three recruiters all approach me in a couple of days for the same position. Just do some shopping around.