A slightly more expensive method would be to hook it up to a mobile phone and periodically send a SMS with the details. Much higher chance of you having mobile phone reception than a WLAN nearby.

Now there's an idea! I have T-Mobile and SMS costs me $0.05/msg, but GPRS is free (in the US at least). So in theory, a modified version of Palantir could connect to my phone's IR port, send an IrOBEX message which an app (that I'd have to write) on my phone would send to my web server via WAP.

Well, it sounds possible, but it also sounds like a lot of work. Even though it'd be free and wouldn't require extra hardware, I think I'd still go for 802.11b. True, there's much less coverage, but I think I have half a chance of actually completing the project