The signing was just announced on Twitter from Jonathan Tamari:
K David Akers has signed with the 49ers #Eagles
Akers is as consistent as they come in terms of kickers. Since joining the Eagles in 1999 he has converted 81.9% (294-for-359) of the kicks in his career, and has made 34 kicks of 40-49 yards since the 2008 season. He has 11 kicks of 50 yards or more in the same time span. Needless to say, he's as steady as they come and one of the veteran kickers in the game.
There has been no word on where the recently cut Nedney will land.