HP has recently released Universal Printer drivers for Windows:
One for PCL and another one for Postscript printers.
Both sets of drivers are very small and can adapt to different printer configurations (such as different trays, supported sizes, etc.).
So why can't they do that for the iPad? It's so simple that other developers have already created printing apps for iPad that don't require a new printer that support ePrint or AirPrint or a printer shared by a Mac or PC.
In reality, you can print a plain text document by using telnet to access port 9100 of a networked HP printer and pasting your text, then exiting telnet.
So why can't Apple at least just add a generic PCL or PS universal driver?
Also, as far as I know, ePrint requires an Internet connection to work, as it uses SMTP to print (is this an accurate statement?).
The day iOS 4.2 is launched, we will know if this rumor was true or false. one thing for sure, I'm not rushing to buy a new printer just to be able to print on the iPad.