April Fools' Day provides the springboard for companies to make some unbelievable announcements, but for Google and Microsoft, it serves as the perfect time to poke fun at eachothers' shortcomings. With Gmail Blue, Google is teasing Redmond over a product that doesn't officially exist yet, while Microsoft goes back to basics to poke fun at its rival's "vanilla" search engine.

"How do you completely redesign and recreate something, while keeping it exactly the same?"

Gmail Blue is said to be the culmination of a challenge to "completely redesign and recreate something, while keeping it exactly the same." While we are left with a distinctly bluer Gmail interface, Google's references to Microsoft's own blue project — Windows Blue — are clear to see, as Microsoft gears up to revamp Windows 8's "metro" mode with new features and some UI tweaks later this year.

For one of its own April Fools pranks, Microsoft fights fire with fire by making Google's iconic start page the target of its affection, serving Bing users with a classic white search page (complete with a multi-colored Bing logo and an 'I'm Feeling Confused' button) when they enter "Google" into the Bing search box. Microsoft also includes the same small boxes found at the bottom of its traditional Bing search page, displaying tooltips including "with so many delicious flavors available, most people still choose vanilla." It's an attempt to advertise its more visually rich search page and perhaps steals some of Google's users in the process, as Microsoft explains: "the main goal here is just to learn more about how our world would look if we hadn’t evolved."

Google's over-the-top dedication to its annual April Fools prank has not gone unnoticed, however. This year, we've seen Google launch Google Maps Treasure Mode, announce the closure of YouTube, and offer the chance to smell search queries via Google Nose, new Google+ emoticons, introduce Google SCHMICK in Australia, expand Google Analytics to include referrals from the International Space Station, offer Google Fiber poles (so far). But Google users have blasted the company for focusing on its April Fools antics, arguing that the time invested in polishing its gags might have been better spent keeping Google Reader alive.