Palm and BlackBerry devices have their own proprietory operating systems similar to non-smartphones, namely Palm OS and BlackBerry OS, but these are both open systems that third-party developers can create applications for. In contrast, you cannot create low-level, natively executable applications for non-smartphones such as the 6610, RAZR V3i, K750i or the X820.
Apple's recently announced iPhone runs OS X and has almost all the features of a smartphone, but it isn't a true smartphone because third-party developers cannot create applications for it. The iPhone will only be capable of installing and running applications released by Apple, making it the iPhone version of OS X more of a proprietary UI than an open operating system. As Engadget said it, the iPhone is not a smartphone.
Palm Treo's run Palm OS, but new ones also run Windows Mobile.
Some phones also run Linux-based mobile operating systems, but not all devices across brands, running Linux-based UIs are compatible with each other. You can't get one application that works with more than one phone, for eg. the Motorola MING, Samsung Qtopia and Yulong Coolpad 858. This is because all thse manufacturers are incorporating their own, customised versions of Linux into their phones, without sticking to any standards, doing away with the openness of Linux and reducing the mobile efforts to mostly proprietary interfaces. The solution might lie in OpenMoko, an open Linux-based platform for mobile phones that's not restricted to a certain brand or company. Xanadux is also interesting; it's a project that's trying to port Linux on to Windows Mobile mobile handsets.
Motorola is also phasing out its P2K UI in favor of the new Linux-based UI which will be incorporated in all their phones from now on. Again, this won't make all Motorola phones smartphones, because even though the code is based on Linux, the features of the interfaces will be limited.
BlackBerry handhelds run Java-based BlackBerry OS
Needless to say, Nokia's Series 60 platform is the most popular. According to Canalys, Series 60 enjoyes upto 72.8% of the smartphone market, followed closely by Linux at 16.7% and Windows Mobile with an abysmal 5.6%. The Linux figure, however impressive, includes non-smartphones also. Nokia's Series 60 is not popular just because it's Nokia - which makes anything they promote popular by default - but because S60 makes the phone in your hand more powerful, compared to Windows Mobile that essentially creates lesser powerful computers in your hand. It's this approach that makes using Series 60 a very natural process for any user.
We hope this article clears up any confusions and misconceptions about smartphones you may have had. If not, use the comments box below to let us know. We are certain that it has also created new questions in your head, for which you can use the forums and we'll try and answer them.
I would like to know if a smartphone can connect to the internet etc with the simm card removed and incur costs. i.e. if you remove your monthly contract SImm card and use in another phone then sell the smartphone to another user will you incur the costs of data connections which it still seems able todo. 
