Front Page Magazine has an interesting interview with Olga Velikanova, a professor of Soviet History at the University of North Texas.
FP: So what is the current situation with the access to the archives in Russia?
Velikanova: Historians can call this situation an “archival counter-revolution.” With Vladimir Putin coming to tenure in 2000, historians noticed a gradual imposition of limitations to access to archives. For example, many files were stalled in “de-classification commissions” and were not given to scholars. I got refusals to my requests to see even those files that I had studied in the 1990s. A "Re-secretizing" process got momentum after 2001 when Putin signed a Presidential decree substituting de-classification commissions with "the Interagency Commission to Defend State Secrets.” Even in the Hoover guide to the CPSS archives, we can see this reverse process - some documents became unavailable and probably were re-classified again. I know the student who had to change the subject of his dissertation because the sources became unavailable again.
I recall a conversation with a Russian historian when I was still at Oregon, who commented that one effect of the various "thaw" periods in Soviet history was the release of some previously-secret documents. Compared to the opening of the archives in the 1990's, these were relatively small,and so each document could be scrutinized carefully and never be effectively made secret again. The current situation is more muddled, because the authorities can lock up things that aren't so well documented. On the other hand, there's still no comparison with the Soviet era, because so much more historical information is now known and will remain known.