I think you should keep at it Nancy. Our kids live in such a technological world and it seems like there are a few of your students that are getting it. Keep in mind there are many different learning styles, and I'm sure that blogging has helped some of your students succeed and go beyond what they normally would have. Frustrating, yes. But those frustrations are well worth it when it helps even just a couple of students find fun in learning!
Matthew, 'I will survive'. I may start again next year with a mandatory vent and see who's doing it because they want to and who is doing it because they have to.
Not a middle school answer, but a senior school approach which seems to be very positive. I set my mob a major essay, but the preliminary work for each student is
0. research a significant community ethics issue (then 3 weeks later)
1. to post a blog (basically a short outline of the topic and the shape of the essay) (4 days later)
2. to comment usefully, helpfully and practically on at least three blogs and then (2 weeks later)
3. produce the final (conventional) essay.
This gave students a heap more input on their topic than they'd normally got, it enabled a few students to shine as collaborators rather than originators. (It also gave me a real chance to ponder a collaborative work assessment criterion with some genuine data instead of guesswork from what I thought I'd heard (I've got bad hearing and poor retention for conversations) with more traditional presentations and discussion.)
What platform you cry? I used a Ning - and they loved the social networking dimensions as well. I'll keep working with this model, it provides genuinely new work dimensions.