Unicorn – Universal Website Validator is a nice new validator tool from the W3C that runs their suite of tests on your site, checking for accessibility and standards compliance.
Try it out for this site! – lots of CSS errors due to my use of vendor specific prefixes, which I personally think, used with caution, should be let through.
Also try out the Mobile Conformance option for an overview of how well your site conforms to mobile device best practices.
If you want to disable the ‘Cut / Copy / Paste’ invoked by holding down on an element in Safari on the iPhone or iPad use the css:
-webkit-user-select: none;
However, as stressed by Apple, this should only be disabled on a per element basis, and never applied to the whole document.
Apple’s Technical Note TN2262: Preparing Your Web Content for iPad covers this along with using web standards instead of plugins (something that really interests me at the moment).