I saw in the paper today an advertisement from Quantum for their new service (jambarr), which lets you send and receive emails from your mobile phone, via a gateway. Check it out - sending emails from your phone deducts from your credit (D1 for each sms, which price includes a reply from the email address); and to send sms from your email address you have to buy jambarr credits, which they say you can get from any Quantumnet Internet cafe. The service works for all the cellphone carriers, which is a big plus. There is a problem with receiving emails as sms though - every time I tried sending an email from my gmail account my phone gave me an error ("Text not formatted as ASCII - could not parse", or something similar). It would be nice if the gateway was intelligent enough to strip out everything but text in any messages it is forwarding, as most emails include images and other non-ASCII characters, which your average user will not know how to turn off.
Of course what will be interesting is what kind of services people build on top of this, social networking or otherwise - I think it has the potential to become big, especially if there's a developer API (hint hint) to allow programmers to build their own services on top of Quantum's.