That would be interesting, indeed.
I've never seen a corporation spring for anything greater than the smallest HDD available, though, so the returns wouldn't be too substantial for anyone on a long-term refresh, though I have seen .5 and 1TB drives shipping recently (and you'd probably want to keep your hands off the SSDs for now). Assuming 100 nodes at an average of 100GB of free space allocation each is perhaps 2TB of questionably reliable storage (10TB of very volatile data). You couldn't allow heavy access to the distributed storage during the day (tanking r/w performance for users). If the licensing and maintenance are very low cost, you could slap 1TB drives everywhere and dedicate half that space for distributed storage. Per 100 users there would be roughly 10TB of relatively redundant space that could be used for, say, deep archives of encrypted backups, logs, or whatever.
Or hell, save space by dedicating a 2nd HDD in every box to distributed storage. A descent SAN will kick its ass any day, but it could potentially cost 1/10th of the price.