I have positive evidence of small(er) firms capturing much of the business lost by the bigger ones. At least 4 management consultancies are now hiring to resource new assignments, with similar signs in some areas of IT consulting.
A further sign of upturn is the emergence of new (!) consulting firms: and I don't mean redundant consultants starting on their own. Successful IT firms, marketing agencies and service businesses are branching into management consultancy, ignorant of all the downturn talk, but close to their client base and aware of needs they are hoping to fill. (Not least, they are also aware of disappointment within their clients from big names).
If you are visiting this site for job opportunities, look out for lesser known names: their recruitment needs are more likely to be real and immediate.
If you are a consulting firm with more projects on your hands than consultants to deliver it, eat some humble pie and check who is available among the people you made redundant not long ago ;o)