I have a SonicBlue replay 4000 and I am hoping to connect it to my 80211b wireless network. I have an extra Linksys Wireless Access Point...is there any way to do this?

It should be as simple as configuring the base station as a transparent bridge and connecting it to the Replay. I'm fairly sure the Linksys base stations can talk to each other (other base stations, that is).

Note that the Replay has 100MB Ethernet, so there may be issues using the wireless solution for streaming video real-time to another Replay.