yes indeed, it's for those ac97 codec chips. In my case i am developing an AC97 Controller (FPGA based) for an national LM4550 Codec IC, datasheet is here: http://www.national.com/ds/LM/LM4550.pdf
The AC97 Serial Link Protocol is described starting at page 18. I mistyped the clock value tho, it's not 81.39 picoseconds but 81.39 nanoseconds, sorry for that.
In short, this protocol packs data in frames of 256 bits length, the frame is divided in 13 so called "slots", the first one 16 bits wide, all other 20 bits. Each bit is clocked at the rising edge of the bit clock from one IC and sampled on the falling edge within the other IC. A Sync signal marks the beginning of a frame. So it's pretty straight forward and should not be that hard to implement.
The Question remains tho, can i add a decoder for this protocol to the picoscope software somehow?