In magento the Matched Expressions are matched on a 'first come, First Served Design' basis.
Thus, if you have Android in the matched expression, any android device will load that design (in most cases the mobile theme)
This is not ideal, as tablets would be able to give a better experience to end-users on the full site.
I use the following setup to target tablets better. The list is not complete, and I would appreciate additional identifiers posted in the comments to make the list more complete.
available on github:
https://github.com/ProxiBlue/MobileUpdates
Place the following code in a module setup sql file, and it will configure the Matched Expressions for you.
<?php
$installer = $this;
$installer->startSetup();
$config = new Mage_Core_Model_Config();
/**
* Matched Expressions configuration settings
*/
$configArray = array(
"design/package/ua_regexp" => 'a:0:{}',
"design/theme/template_ua_regexp" => 'a:8:{s:18:"_1373444133830_830";a:2:{s:6:"regexp";s:4:"Silk";s:5:"value";s:7:"default";}s:18:"_1373444140765_765";a:2:{s:6:"regexp";s:6:"Kindle";s:5:"value";s:7:"default";}s:18:"_1373444151317_317";a:2:{s:6:"regexp";s:4:"Xoom";s:5:"value";s:7:"default";}s:18:"_1373444158789_789";a:2:{s:6:"regexp";s:8:"SCH-I800";s:5:"value";s:7:"default";}s:18:"_1373444170390_390";a:2:{s:6:"regexp";s:6:"Tablet";s:5:"value";s:7:"default";}s:18:"_1373444173174_174";a:2:{s:6:"regexp";s:5:"TF101";s:5:"value";s:7:"default";}s:18:"_1373446849536_536";a:2:{s:6:"regexp";s:5:"MZ604";s:5:"value";s:7:"default";}s:18:"_1373447225646_646";a:2:{s:6:"regexp";s:110:"(Android|iPhone|iPod|BlackBerry|Pre|Palm|Googlebot-Mobile|mobi|Safari Mobile|Windows Mobile|mobile|Opera Mini)";s:5:"value";s:6:"iphone";}}',
"design/theme/skin_ua_regexp" => 'a:8:{s:18:"_1373444271536_536";a:2:{s:6:"regexp";s:4:"Silk";s:5:"value";s:7:"default";}s:18:"_1373444274847_847";a:2:{s:6:"regexp";s:6:"Kindle";s:5:"value";s:7:"default";}s:18:"_1373444279303_303";a:2:{s:6:"regexp";s:4:"Xoom";s:5:"value";s:7:"default";}s:18:"_1373444283311_311";a:2:{s:6:"regexp";s:8:"SCH-I800";s:5:"value";s:7:"default";}s:18:"_1373444287440_440";a:2:{s:6:"regexp";s:6:"Tablet";s:5:"value";s:7:"default";}s:18:"_1373444291591_591";a:2:{s:6:"regexp";s:5:"TF101";s:5:"value";s:7:"default";}s:18:"_1373446817839_839";a:2:{s:6:"regexp";s:5:"MZ604";s:5:"value";s:7:"default";}s:18:"_1373447246734_734";a:2:{s:6:"regexp";s:110:"(Android|iPhone|iPod|BlackBerry|Pre|Palm|Googlebot-Mobile|mobi|Safari Mobile|Windows Mobile|mobile|Opera Mini)";s:5:"value";s:6:"iphone";}}',
"design/theme/layout_ua_regexp" => 'a:8:{s:18:"_1373444328624_624";a:2:{s:6:"regexp";s:4:"Silk";s:5:"value";s:7:"default";}s:18:"_1373444334264_264";a:2:{s:6:"regexp";s:6:"Kindle";s:5:"value";s:7:"default";}s:18:"_1373444341272_272";a:2:{s:6:"regexp";s:4:"Xoom";s:5:"value";s:7:"default";}s:18:"_1373444347376_376";a:2:{s:6:"regexp";s:8:"SCH-I800";s:5:"value";s:7:"default";}s:18:"_1373444355756_756";a:2:{s:6:"regexp";s:6:"Tablet";s:5:"value";s:7:"default";}s:18:"_1373444363137_137";a:2:{s:6:"regexp";s:5:"TF101";s:5:"value";s:7:"default";}s:18:"_1373446814359_359";a:2:{s:6:"regexp";s:5:"MZ604";s:5:"value";s:7:"default";}s:18:"_1373447249810_810";a:2:{s:6:"regexp";s:110:"(Android|iPhone|iPod|BlackBerry|Pre|Palm|Googlebot-Mobile|mobi|Safari Mobile|Windows Mobile|mobile|Opera Mini)";s:5:"value";s:6:"iphone";}}',
"design/theme/default_ua_regexp" => 'a:8:{s:18:"_1373444329425_425";a:2:{s:6:"regexp";s:4:"Silk";s:5:"value";s:7:"default";}s:18:"_1373444334920_920";a:2:{s:6:"regexp";s:6:"Kindle";s:5:"value";s:7:"default";}s:18:"_1373444340392_392";a:2:{s:6:"regexp";s:4:"Xoom";s:5:"value";s:7:"default";}s:18:"_1373444346680_680";a:2:{s:6:"regexp";s:8:"SCH-I800";s:5:"value";s:7:"default";}s:17:"_1373444358048_48";a:2:{s:6:"regexp";s:6:"Tablet";s:5:"value";s:7:"default";}s:18:"_1373444365409_409";a:2:{s:6:"regexp";s:5:"TF101";s:5:"value";s:7:"default";}s:18:"_1373446810975_975";a:2:{s:6:"regexp";s:5:"MZ604";s:5:"value";s:7:"default";}s:18:"_1373447252330_330";a:2:{s:6:"regexp";s:110:"(Android|iPhone|iPod|BlackBerry|Pre|Palm|Googlebot-Mobile|mobi|Safari Mobile|Windows Mobile|mobile|Opera Mini)";s:5:"value";s:6:"iphone";}}',
);
foreach ($configArray as $key => $value) {
$config->saveConfig($key, $value);
}
$installer->endSetup();