I recently downloaded Internet Explorer 8 RC1 and was playing with the InPrivate Filtering feature. I think that this feature could be used as an Ad Blocker. I converted the adblock plus filters into xml format understood by IE and imported them in the InPrivate Filtering settings. Many websites worked fine while some (e.g. yahoo mail) appeared to be broken. I am sure that with a little tweaking of the rules it will be possible to get better results.
You can get the xml file I generated here.
Alternatively, you could paste your adblock rules in the text area below and click submit. You will get back the xml content in the same text area.Edit InPrivate filtering options that can be found in right bottom corner in IE 8. Go to advanced options and import the xml file just created.