With Firefox 3 already in the third iteration of its beta, Microsoft appears to be feeling the pressure of getting the next version of its web browser out the door. Therefore, it has sent out invitations to a select number of testers allowing them to participate in a “limited technical beta program” for the upcoming Internet Explorer 8, while at the same time announcing that a public beta is due soon.

Aside from the program announcement, no details regarding the browser’s new features were available. Microsoft, however, has previously revealed that it passes Acid 2 – the de facto industry test for standards compliance – and will introduce the controversial “version tag” to properly render websites that have been coded to work around the shortcomings or outright errors in IE6.

Microsoft executives are expected to reveal further details about the browser’s features at the software maker’s upcoming Mix conference in Las Vegas next week.