As has been mentioned on some message threads recently, the CRB is changing shortly.
DBS is the new name for the CRB and is the CRB merged with the remains of ISA from what I understand.
HomeOffice: Vetting and Barring Scheme has more information about DBS.
One thing of interest to many people I suspect is the Update Service, which is planned for launch sometime in 2013.
Details don't seem to me to be fully determined at this stage but the Update Service should allow an applicant to apply for a check once and then employers can check online to see if the information on the certificate is still up-to-date. Fees for that have not yet been announced and not clear if the applicant (so nanny, childminder) would be paying the fee, or if it would be the employer (in the case of a nanny) who would pay a fee.
We will need to wait and see but perhaps the DBS will finally mean that childcare workers can get just one check (which gets updated) and then have employers see online that the check is still valid.
Would you pay more for a check that is constantly updated and employers could access, than a printed certificate that you get for each new job?