Of course I am sure you know if they are not DRMed you can convert them with Calibre. I am assuming though you mean the ones in secure ereader format from Fictionwise or the DRMed ones from ereader.com. Those can't be converted. I have let a mod know that people aren't happy about this, though I am sure they are aware of this from the posts about it. I did try to send an email to customer service, but it wouldn't go through.
That would be an elegant solution to the problem--they don't have to try and convert previously purchased books to a new format, but that would go a long way towards satisfying long-term loyal customers.
I'm in the same position as you, I have more than 700 titles from eReader/Fictionwise that I would like to read on my new NOOKcolor. I think it's simply wrong: the technology is there (the original nook was secure eReader compatible) but the new device doesn't support the same format used by two wholly owned subsidiaries of B&N.
One of the best illustrations of why we need to get rid of DRM--it only punishes the paying customers, and does absolutely nothing to stop piracy.
It is something that should be addressed. The word from Nook_Engineer is that he has expressed the request to all the right people. He also said that sometimes decisions such as this aren't quick in coming.
Why no one will at least say why such a decision was made in the first place is beyond me, but it doesn't seem to me it should be so hard. I can understand them not wanting to let loose with some type of conversion program, but they could either allow the format to stand as is and support it or do the conversions themselves and offer that to customers of their companies.
Or, of course they could do what customers have begged them to do for a long time now-merge the libraries with the BN one.