Marketing with social media is not something I've ever thought about before, and being new to a lot of the social media we've been looking at and not knowledgeable about marketing, either 4Ps or 4Cs, I'm not too sure where to start.
I have checked out the Slideshare presentations about it and can see that it could be a useful tool to use to promote yourself, your business, your country etc.
Since starting 23 Things, the department where I work has set up a Facebook page," 'cos everyone's doin' it!". It is being regarded as a place to communicate in a more informal manner with people than using the face we present on our website (not that the FB page has been publicized there yet. Where's my to do list?). And, I believe that there are some whispers going around about a possible department blog being set up, but there is nothing concrete happening on that front just yet. The worry is, is that these things are set up but not followed through when there's either not enough info to fill the space, and time and/or money is tight.
If you have the right resources to invest in setting up your marketing potential through web 2.0's social media, then I think it can be an effective way of communicating with new and existing clients. But things get out of date quickly and once started I think it's crucial to be disciplined about regularly updating and reviewing content.