several ways you could handle this…
first, do you want all images in your wp site in a p tag to be floated left?? never really understood that in themes… I like to place my images in different locations instead of hard coded to fix location… you could try removing the float and see if it messes anything up on your site…
second, you could just fix it in your spf theme, in this case structured-tan… in the skin css file, at line 19, you could add a float: none; directive which would do the same thing…
If you go the second route, I would suggest copying the skin over to your own skin to protect against upgrades overwriting your changes… name the new skin directory whatever you want, just make sure the css file name itself matches the directory name…
I think I will also open a ticket to consider adding the image float none directive to our skins to keep this from happening again…