That may be true (I don't know), but is it really effective? Are there many DRM schemes that have been out for more than a few months and haven't been cracked yet?

In the case of the N900 it's hard to point to lack of DRM as the cause when there are so many other good reasons for commercial developers to not bother (small target market compared to competition, Ovi store brokedness, still-born platform). The ones that did bother (eg Rovio or Sygic) generally seem happy with the return on their investment even without DRM.

We know DRM will come in Harmattan. We also know it will be possible to flash a different kernel, but doing so will deactivate the hardware support so DRM "content" will stop working. Which means as soon as you step outside the official signed Nokia kernel for whatever reason (maybe you want some unsupported filesystem, or IPv6, NAT, KEXEC, you get the idea) you stop being a potential customer. I wonder whose foot exactly is getting shot by this...

Yes, I'm not here to argue the merits or effectiveness of DRM. Just pointing out the driving factors that can easily be observed in today's marketplace.

So, the developers may think that:

a). DRM works.
b). There's no better solution yet than DRM, so that'll do for now.
c). DRM is 'cheap' enough to implement for the incremental solution that it presents
d). all of the above

Any of which will drive them to opt for DRM than to release their code 'naked' into the wild.

As for Harmattan; I'd imagine the 'jailbreak' will allow DRM-ed contents to be utilized on the non DRM-ed 'side'.

IMO DRM stimulates, not deter, the so called "piracy"

If a door is not there does it mean it is impossible to open it?

The sooner manufacturers/publishers realise DRM wouldn't work the better it would be for paying customers. DRM only hurts customers, pirates don't give a toss (in any case most pirated versions work better than the original because of the removal of the DRM). How do you get manufacturers to drop DRM? Simply don't buy DRM'ed products.