Reading the Google Tea Leaves has Tristan Louis doing a nice job charting various search and portal features that the major services offer, reminding me exactly what I used to do back in the late 90s. But maintaining those charts is a nightmare! If you need a quick rundown, definitely check it out. Tristan also uses the charts to speculate on what products Google might offer. No real revelations there, however.
Audio search? Sure, that's kind of obvious without the charts and overdue, especially with Yahoo's continued expansion.
An encyclopedia partnership? Google kind of has that already with the existing Answers.com deal, which sometimes brings up encyclopedia info along with dictionary definitions, including that from Wikipedia. Plus, it's hard to do a search these days it seems and not run into Wikipedia on the first page of Google results.
Google also talked with Wikipedia about a hosting deal, though I don't recall seeing anything further on that. FYI, Yahoo did do a partnership with Wikipedia, but looking today, that seems to have ended, with the Columbia Encyclopedia being used instead.
Clustered results? Google's got the technology already, just not the desire to use it nor really a pressing need since clustering's hardly been a category killer (Ask Jeeves used to offer it. So did FAST. Clusty still does. None of them have seriously rivaled Google for traffic).
Calendar? Again, obvious portal feature, especially for a company with a mission of helping people organize information. So much info is calendar driven that this is a necessity. Jeremy Zawodny asked for one earlier this year, and we've had recent signs one may be coming.