Patti and I were discussing our ePortfolio project the other day, and we were basically throwing back and forth various versions of "the students won't it because (a) they don't have to, and (b) it's not theirs."
The "they don't have to" part could be misconstrued as meaning "their profs didn't make them do it." That won't work, either. The students have to feel that they want to do this. That they have to do it themselves to make sense of what they're learning and doing.
And, it needs to be modelled successfully. If they see their profs as not "having to" maintain an ePortfolio, why on earth would the students do it? It's not some contrived evaluation tool, it's an internally driven amplifier and archiver of the learning (and teaching) processes.
Helen Barrett just posted a piece that describes this much more coherently, and in much greater depth. The mental picture of the graduation portfolio bonfire should be a big reminder about what can happen when there isn't a healthy sense of ownership fostered within students (and teachers). I remember burning my notebooks at the end of grade 9 - they weren't MY notes, so it felt awesome to toss them on the bonfire... Stephen's commentary is worth a read, too.
This is all about ownership. But ownership can't be given, it has to be built by each individual. It would be so easy to just say "it's a requirement to complete this course/program. you must maintain an ePortfolio." But that won't work. It will just lead to a lot of busywork, and one helluva bonfire at the end of the course/program.
I think the more effective (from a teaching/learning perspective, not a sheer volume/metrics perspective) is to model the ePortfolio as a teacher. "This is how I gather my thoughts together to track what I've done, what I'm doing, and where I'm going in my career as a teacher". If it's not relevant to a professional, why would it be relevant to a student?
Offer ePortfolios as an optional service across the curriculum, to every student on campus. If 1% of them start using them as effective tools, it will spread from there. Not instantly, and maybe not in the same cohort, but it will spread.
If it doesn't spread, it's not an effective tool, so let it die on the vine. The goal is to foster critical thinking about experiences, not to force yet another tool on anyone.