There is unofficial information from the Russian government offices that on the Friday evening prime minister Mikhail Kasyanov applied on resignation.
The same source informs that on this Saturday a meeting with president Putin was delayed for two hours because Kasyanov, not feeling himself a prime minister anymore, refused to come. He did come at the end of the meeting, after a personal telephone call from the president to the (ex?) prime minister.
Should his resignation be approved, this creates a very difficult situation before the elections. The problem is that according to the Constitution, president has to present a new candidate for Duma to be approved in two weeks. However, in two weeks exactly there are lections to Duma itself, and quorum is technically difficult. Also, the new prime minister legitimacy will be under fire from the new parliament. The new parliament in its turn will not have time to gather and approve a new prime minister within the time written out in the Constitution. So, the country can approach elections with an interim prime minister and a breach of the Constition.