Hrmm. Both of the optical mice (one wireless, one wired) I've taken apart recently did NOT appear to have an agilent chip in them (agilent doesn't seem to have any chips like this one...*sigh*).
Instead, they have a 44 pin surface mount IC, in a (completely) clear epoxy/plastic casing, with NO markings of any kind on it...It's pretty...but largely useless, since I haven't been able to find any kind of a datasheet for it. It appears to have a pretty large imaging area, which is totally visible once you take the black ABS shield off of the chip.
Has anyone seen or heard anything about this chip? Both of them were MS optical mice (The one I still have a case for is a Microsoft Intellimouse Optical USB and PS/2 mouse (which had a button sporadically failing), the other was a wireless MS optical mouse that lost connection between the hardware, and the internal (cheap) antenna)