Nearly all the upcoming tablets from outfits like Cisco ( CSCO), RIM and Samsung are 7-inch touchscreen devices. It is a size that Jobs says is too small for adequate tablet use. This crucial point comes from the developer of incredibly popular small-screen devices like the 3.5-inch iPhone and iPod touch. Apple currently owns the tablet market with its 9.5-inch iPad that sells for between $500 and $800. The onslaught of smaller rival tablets will likely bring much lower prices and, of course, fragmentation. Apple shares were down 2% to $311.64 in late-morning trading Tuesday as investors were banking some of their recent gains and buyers were shopping for lower entry points. --Written by Scott Moritz in New York. >To contact this writer, click here: Scott Moritz, or email: firstname.lastname@example.org. To follow Scott on Twitter, go to http://twitter.com/TheStreet_Tech. >To send a tip, email: email@example.com.