IE7/IE8

The selectors and properties below should all work according to the W3C specifications.

IE7.js

CSS Selectors

SelectorCommentsTest
parent > child html
adjacent + sibling html
adjacent ~ sibling html
.multiple.classesIE5/6 bug fixed (also applies to pseudo classes)html
:hover html
:first-child html
[attr] html
[attr="value"] html
[attr~="value"] html
[attr|="value"] html
[attr^="value"] html
[attr$="value"] html
[attr*="value"] html

CSS Properties

PropertyCommentsTest
background-attachmentsupport fixed positioninghtml
background-imagePNG alpha transparency (IE5.5+)html
bottomheight implied if top is suppliedhtml
cursorsupport pointer for IE5.xhtml
displayconvert list-item to block for IE5.x 
font-sizefix named font sizes (IE5.x)html
marginsupport auto (IE5.x)html
max-height html
max-width html
min-heightimplemented for IE5html
min-width html
overflowsupport overflow:visiblehtml
positionsupport fixed positioninghtml
rightwidth implied if left is suppliedhtml

HTML

ElementCommentsTest
abbrIE5/6 bugs fixedhtml
imgPNG alpha transparency (IE5.5+)html
labelbind to the first child controlhtml

Other Bug Fixes

BugCommentsTest
Doubled Margin*Position Is Everythinghtml
Peekaboo*Position Is Everythinghtml
Unscrollable Content*Position Is Everythinghtml

*These fixes are not in the standard IE7 library. They are included in a separate module ie7-squish.js.

IE8.js

CSS Selectors

SelectorCommentsTest
::after html
::before html
:active html
:focus html
:checked html
:contains() html
:disabled html
:empty html
:enabled html
:indeterminate html
:lang() html
:last-child html
:not() html
:nth-child() html
:nth-last-child() html
:only-child html
:target html

CSS Properties

PropertyCommentsTest
border-spacingHTML tables onlyhtml
box-sizingcontent-box (assumed)html
contentSupports the use of attr() and url()html
opacityIE5.5+html
property: inheritSupport for inherited property valueshtml

HTML

ElementCommentsTest
button[type=submit]value submitted rather than innerTexthtml
formonly submit successful controlshtml
objectimproved support for type=image/*html