The reason why network-ready all-in-ones can't scan over network is because of file sizes. When a document or photo is originally scanned in, the file starts as being uncompressed and thus VERY big (on high-res photo scans, we're talking images that can be 100 MB+ uncompressed!). Imagine doing that over a network... On 802.11b it might work so-so, but it's completely unrealistic at BlueTooth speeds.
If you plan on using a BlueTooth adapter on your printer, you'll need to double-check to see if it's compatible with that. I know a few Epson models can do it, but you have to buy their BlueTooth print adapter that costs around $80. Supports print only.