IPhone – Why does the Gmail signature on the iphone default to the gmail app on the ipad

Here are the steps to make this work, even tried them on Mac OS X 10.7 Lion GM / Mail.app 5.0

1. Open Mail.app
2. Create a signature
3. Close Mail.app
4. Open Terminal and in Leopard/Snow Leopard go to ~/Library/Mail.app/Signatures, in Lion it's in ~/Library/Mail.app/V2/MailData/Signatures/
5. You'll find there a file with random digits such as: 4E725456-58C1-4FD7-8490-3048F994CC33.webarchive
6. Open that file in Safari, use View Source or Inspect to get the HTML content
7. Create a new file using your preferred editor, I used nano, and paste the html
8. Look for 'font-size = medium' and change it to the size you want, i changed it to 12px to match my Tahoma 12px mail font
9. (Optional) if you want to embed an image, call it using <img> to a remote, public location and remove all <object> </object>
10. Save the file as .html
11. Open that .html file in safari and save as .webarchive
12. cp the .webarchive you created to the location of the original .webarchive file while keeping the correct name (replace it)
13. Open Mail.app and check that the signature is the way you want it...

iOS only supports a single signature, but you can use iOS 5's new text Shortcut feature to manage multiple signatures. The feature is in the Settings app under "General | Keyboard | Shortcuts".

Add a shortcut for each signature, e.g. wsig = Work Signature and psig = Personal Signature

Shortcut only supports single lines of text, so I get around this by having my default sig be my name plus a new line, then I type the shortcut text on the blank line after my name.