Time's up! No cookie for you. The answer is: both series have new installments rumored to be on the verge of seeing announcements.
First up is the last-page teaser in the latest issue of Edge, which simply shows a full-page spread of grass (the kind on your lawn) with the simple phrase "Next month." GoNintendo busted out the magnifying glass, and points to a small purple shape on the right side of the page that they claim indicates the reveal will be related to a new Pikmin game. That seems like a small leap in logic, but then, Nintendo did mention briefly at last year's E3 that a new Pikmin is in the works. With the next E3 looming and the previous Pikmin games appearing in enhanced form on the Wii, now seems like as good a time as any to bust out a new one.
Shifting gears to a series that's about as different from Pikmin as you could possibly find, Shacknews offers a trail of evidence via various Eidos comments and advertisements (the latter again appearing in Edge) that the company will announce the next Thief game, said to be in development at its Montreal studio, a week from today on Monday the 11th. This one seems like way more of a sure thing; the clues offered by Eidos itself are almost irrefutable.
I'm going to be painfully honest here: other than some brief prerelease preview coverage, I've never played a game in either one of these franchises. Go on, judge me. Better late than never, though, right? Are you excited for either one of these, if they get announced?