I think you assume wrong, as some people have reported that 1GB cards
have worked.  A lot of people have 512MB cards working no problem
though.
--
Munch

I got a 512 card to work by formatting outside phone in  a reader writer
which i bought for about ?18. It now acts as a decent mp3 player in the gym

According to the changelist from 3.17 to 4.28 on the 6230 firmware, it
specifies "Improved compatibility with 512MB MMC cards." and "Memory status
displays correct free/used/size for 512MB MMC cards.". A friend's 512MB card
works my phone, but not in his. He has 3.17, I have 4.28. The problem with
512MB MMC cards not working is more related to the way MMC bus is addressed.
The page size doubles for the first time when you get to a 512MB MMC card
and hence a different addressing scheme has to be used. This is also why,
for people with firmware 3.17 or lower, on the 512MB cards that do work, the
phone displays the incorrect size for a 512MB card, as it only detects half
of it and the page size is simply doubled, giving the full 512MB size and
compatibility.

The list that I made a couple of weeks ago about compatible MMC cards for
the 6230, the one you said couldn't be written and wouldn't be of any use,
clearly shows several brands of MMC 512MB cards that don't work on v3.17,
but DO work on 4.28.

It's to do with the way 512MB cards are addressed by the firmware, not to do
with the pins of the card. The pin definitions are the same for any size MMC
card.

Unless it's a dodgy MMC card in the first place, upgrading to 4.28 will
allow a 512MB MMC card to work in the majority of cases.

Adam