The Mobile Handset Analyst discusses the problem of the carriers which compress the images taken by Megapixel cameras. And yes, this is a big problem as soon as you want to moblog quality pictures. With the GX-30 for example, I get pictures at 200-300 KB, but when I send them I have first to compress them as more than 100 KB are not allowed in MMS. The Mobile Handset Analyst concludes:

The issue is likely to come into sharper focus next year with the launch of two- and three-megapixel devices. “We’re in a situation now where MMS is always catching up,” Wood says. “MMS is still a very good framework for sending messages from one phone to another, but if people are going to want to send print-grade pictures, then operators need to think about using an e-mail or GPRS bearer.”