the bone stock mms apps don't do the slide show, and I dont mean bone stock as the ones that came with your phone that have HTC sense, motoblur, etc. etc
I mean the ones that came with pure android. N1, NS.
If you install the latest Gingerblur you get this functionality. No more slideshows.
Alternatively, ive attached the mms.apk that gingerblur installs. You gotta have root + sideloading capabilities.
rename /system/app/conversations.apk to conversations.apk.bak
copy mms.apk to /system/app
then just fire up your mms app as normal. It looks totally different. if you had the mms app on your homescreen it's now gone. you have to put it there again
I DO NOT KNOW IF THIS WILL WORK WITHOUT THE COMPLETE GINGERBLUR PACKAGE INSTALLED. ATTEMPT AT OWN RISK. although i don't really see the harm in it. if it doesn't work i would imagine just rename mms.apk to mms.apk.bak, and revert conversations.apk.bak back to converstaions.apk