Here's one that might show promise. http://reviews.digitaltrends.com/review1549.html
It's a bluetooth enabled camera - meaning it can transmit it's picture to a PDA, Phone, or PC somewhere.
I think the hard part of overcome is not having an actual computer to transmit the data.
If you wanted to carry a laptop with an air card, it could be done yeah. Or perhaps if you wanted to affix one in your car. I suppose you could use a camera in the grille like a police cruiser, then tie the camera to the laptop, and use the air card to stream the images to a media server or FTP location.
Typical air cards run about 60 a month now, perhaps $250.00 to buy the card itself. You would need a computer on the 'other end' somewhere set up to accept the images. The Aircards offer close to broadband connection speeds in major cities, but if you get out of a major city, you'll slow to modem speeds. Image quality will determine how feasible it would be to transmit data under various conditions like that. High quality will need a lot of bandwidth, a typical 'cell phone' camera type of picture, say 320x240 type of resolution should be able to move fine over broadband even with a few 'hiccups' here and there. Slower Modem speeds... ehh, maybe.
I did managed to find a streaming app that let's you watch a remote camera - this would be best - to stream the data... http://www.deskshare.com/Resources/articles/wcm_viewcameraremotely.aspx
I suppose it could be set to record the feed somehow, not 100% sure - I didn't look specifically into it. If not, I googled "send camera feed to a remote location" - there were a lot of hits.
There are also IP based cameras but most of those will require a wireless router nearby to work, or possibly a wireless crossover, I've never attempted that or even know if it works.
Might want to check this site out on that - about 'Ad Hoc' Wireless networks - funny I should run across that page, lol. http://w3.antd.nist.gov/wahn_home.shtml