Android 3 (Honeycomb) has a lot of cool efficiency enhancing features, one of which is tabbed browsing. Honeycomb brings tabbed browsing to the native Chrome browser that provides powerful browser functionality normally reserved for a laptop.
There are two basic ways that you can open a link in a new tab:
1.) Long tap a link (I have found that a one second delay works well)
2.) Tap and hold to bring up a menu of options, then tap Open in new tab
Of course you can simply tap a link to open it in the current browser window.