IE10 will be released as part of Windows 8 in October and will be released later for Windows 7.
When IE10 is released or if you have either the Windows 8 Release Preview or the earlier IE10 Platform Preview, there are at least two things, below, that you should look at.
1) Check your ASP.Net sites run correctly
It should be obvious if this happening because some ASP.Net functionality (postback events) won't work.
So for example, if you have a drop down list that triggers something else when the selection changes, this will fail. If in doubt, copy the test code from this page onto a clean page of your own, upload it to your server and open it in IE10 (and another browser for comparison).
If you find postbacks failing you'll need to contact you host company ASAP. If they don't understand or recognise the issue, refer them to this page.
This explains the issue and has links to the Hotfixes
2) Switch off compatability mode for intranet sites
If you locally preview a site that uses HTML5 and CSS3 features (placeholder text, round corners etc) in IE10, using the EW Development Server or IIS, you may find that these features don't display.
This is because the default browser mode for intranet sites in IE10 is 'Compatability mode'. You can change this in 'Tools - Compatability View Settings' . Uncheck the 'Display intranet sites in Compatability View' option.
Now you'll notice that there is also a setting 'Display all websites in Compatability View'. What happens to your site if a user has this checked, intentionally or unintentionally? Your site won't display properly.
You can avoid this problem by forcing IE10 into it's highest or 'Edge' mode. You do this by adding the following meta tag to your pages or the DWT / ASP.Net MasterPage.
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
It's worth adding this to the existing IE Meta Tag snippets in EW V4.