Is BitLocker security being evaluated?

Yes!

BitLocker is included in the Windows Vista / Windows Server 2008 Common Criteria EAL4+ evaluation.

Windows Vista BitLocker has already been FIPS 140-2 certified.

https://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140val-all.htm

Windows Vista SP1 BitLocker and Windows Server 2008 BitLocker are currently in FIPS 140-2 evaluation.