Don't forget that if you use any cloud print service, such as Google's, you will have to change your firewall to enable the service to access your PC (or IP-enabled printer) directly through your router.
Google's service doesn't work that way. You can only print through Google's service if you are signed up to Google, and if you're running the Google Chrome Browser. You have to enable Google Cloud printing in the Google Chrome settings.
Another way of printing from your smartphone (or any other PC for that matter) is to buy one of the new printers which has its own email address. The new HP ePrint printers have their own email addresses on HP's own servers, and will print a picture attached to an email. These printers do not need a PC to do this, and because the pictures to be printed are in the form of email attachments, there is no need to alter your router settings.
At the moment Argos are selling the HP 5510 e-All-In-One Wireless-n/USB Printer/Copier/Scanner for £69.99, which is remarkable value.