The latest grist from the rumor mill places a fresh alternative to the Apple (Nasdaq: AAPL) iPad in the third quarter of 2010. But don't forget about all the others!

Batten the hatches!
According to Examiner.com, Hewlett-Packard (NYSE: HPQ) wants to get a tablet device in time for the holiday shopping season. Codenamed "Hurricane," this replacement for the ultimately bloated, battery-busting, and canceled Slate tablet should sport a webOS software platform courtesy of HP's just-announced Palm (Nasdaq: PALM) acquisition.

Unlike Microsoft's (Nasdaq: MSFT) Windows 7 operating system, which ran on the scrapped HP Slate, webOS was built for smartphones. This means high attention to details such as battery life, touchscreen usage, and mobile connectivity. The Intel (Nasdaq: INTC) Atom chip was named as one of the reasons for the Slate's lackluster performance, but webOS runs on the competing ARM chip architecture, which is more widely accepted by the smartphone industry. I suppose that webOS could be ported over to Intel's platform if the new Atom chips fit the bill, but there's really no need to bend over backward like that. HP has the technology it needs to make a splash here.

All in all, a webOS-based Hurricane tablet from HP makes plenty of sense and I would be shocked if it didn't happen. But ...

If a tablet falls in the market and nobody notices, did it make a sound?
See, the tablet space is apt to be much more crowded this fall than you might think. The iPad is just the first tablet on the market that's powered by a truly mobile set of hardware and software, and there are lots more coming from every corner.

Maybe you forgot about Google (Nasdaq: GOOG)? The Android operating system could easily show up on a range of tablets before you know it, providing an experience similar to what Apple and this newfangled HP/Palm gadget can do.

But that's not all from Big G: Chrome OS hasn't made many waves lately, but Google has said that "netbooks running Google Chrome OS will be available for consumers in the second half of 2010." Hardware partners include HP, Toshiba, Acer, and Lenovo, so we're likely to see multiple vendors offering Chrome OS tablets soon enough. Yes, HP could be hedging its bets here. And if Android and its rivals were built for smartphones, Chrome OS simply puts the Web on a tablet, glued to a touchscreen and a battery. Simpler may be better when it comes to stretching battery life and creating a clear user experience.

Fellow Fool Tim Beyers feels that Google made a mistake by committing to two separate mobile platforms, but I'm not so sure. Yes, Android and Chrome OS overlap to some degree, but they are ultimately aimed at very different and clearly defined market segments. If all you need is a portable Web browser, Chrome OS is your thing. For the full application-infused mobile computing experience, there's Android.

But wait -- there's more!
Of course, Microsoft won't give up without a fight. The Windows Phone 7 platform will eventually make its way into tablet computers in the iPad vein, though perhaps not in time for Christmas shoppers. And while Android, webOS, and Chrome OS all are based on the Linux operating system, the openly penguin-powered Ubuntu Mobile Internet Device edition is getting fine reviews in the concept stage -- and the backing of Intel.

Heck, even Research In Motion (Nasdaq: RIMM) is supposedly working on a BlackBerry-flavored tablet, and there's more from other manufacturers, too. But let's cut a long story short and simply jump to the obvious conclusion: The iPad will not be your only choice for tablet computing goodness for much longer.

On my signal, unleash hell!
This is shaping up to become a bloodbath. Consumers will be swift to vote with their wallets, and the pretenders will quickly fall away from the true winners. The iPad got a head start and caters to a crowd of raving fans, which adds up to a leadership position. One or both of the Google-approved platforms should make a serious dent in the market. Windows Phone is running late, and the rest are mere mirages at this point; seeing them in the real world will be a pleasant surprise.

So let the games begin. My money is on the iPad with Android tablets breathing down its neck this fall, but the comments box below is eager to see what you think.

Fool contributor Anders Bylund owns shares in Google, but he holds no other position in any of the companies discussed here. Intel and Microsoft are Motley Fool Inside Value selections. Google is a Motley Fool Rule Breakers recommendation. Apple is a Motley Fool Stock Advisor pick. The Fool has created a covered strangle position on Intel. Motley Fool Options has recommended a diagonal call position on Microsoft. Try any of our Foolish newsletters today, free for 30 days. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.