Hi Guys
I just noticed and fixed this in a site I am working on, then found this thread. It seems like a rediculous decision to have removed the style attribute as it means that half the buttons on the top row of the toolbar now don't work, for example the text alignement on paragraphs wont work, nor will underline or italic. If the idea is to encourage using classes then remove the buttons that no longer work, rather than confusing people.
Anyway rant over, I just stuck this (very long) line in my Page.php getCMSFields() function to fix it (no need to edit LeftAndMain.php):
HtmlEditorConfig::get('cms')->setOption('valid_elements', '+a[id|rel|rev|dir|tabindex|accesskey|type|name|href|target|title|class|style],-strong/-b[class],-em/-i[class],-strike[class],-u[class],#p[id|dir|class|align|style],-ol[class|style],-ul[class|style],-li[class|style],br,img[id|dir|longdesc|usemap|class|src|border|alt=|title|width|height|align|style],-sub[class],-sup[class],-blockquote[dir|class],-table[border=0|cellspacing|cellpadding|width|height|class|align|summary|dir|id|style],-tr[id|dir|class|rowspan|width|height|align|valign|bgcolor|background|bordercolor|style],tbody[id|class|style],thead[id|class|style],tfoot[id|class|style],-td[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],-th[id|dir|class|colspan|rowspan|width|height|align|valign|scope|style],caption[id|dir|class],-div[id|dir|class|align|style],-span[class|align|style],-pre[class|align],address[class|align],-h1[id|dir|class|align|style],-h2[id|dir|class|align|style],-h3[id|dir|class|align|style],-h4[id|dir|class|align|style],-h5[id|dir|class|align|style],-h6[id|dir|class|align|style],hr[class],dd[id|class|title|dir],dl[id|class|title|dir]
,dt[id|class|title|dir]');