You may or may not know that iOs 4.2 lacks the quality to print to a shared printer connected to your Mac. Apple had the traditional intention to contain this quality but decided to strip it from the final publish of iOs 4.2. So we can now only print from our iPhone's, iPod touch's and iPad's to prime printers which have wireless (walk up technology) printing onboard.
Luckily Printopia solves this problem. The Application installs itself on your Mac within the theory Preference panel and allows you to plump which printers connected to your Mac (also lets you use network printers) to be usable from an iOs device. The interface to set all this up is for real just ticking the boxes of the printers you want to be shared, very very easy to use.
Once you've ticked a printer you can start printing web pages, emails, notes, iWork documents etc. Facts is sent from your iPhone and iPad very quickly straight through the Mac and to the printer of choice. I have used a huge variety of printers and they all print out what I have told them to identically, so it is consistent one of my traditional worries.