can i transfer my keynote doc to my ipad3 for presenting?

Yes it is possible. You should be aware of a few things:

1. You will need Keynote for iOS installed on your iPad3 - this is available from the App Store in iTunes
2. The Help File in the iOS version of Keynote under the Tools Menu (wrench) will give you instructions on how to transfer the file to your iPad3
3. There are some differences between how presentations work on your MBP and your iPad3, not all fonts, actions, builds or transitions work on the iPad - see this file for good guidance on best practices: http://support.apple.com/kb/HT4114
4. Depending on your venue, you may need additional cables to work with projectors, etc.; if you have a newer generation Apple TV connected to a projector or HDTV, you can wirelessly transmit your presentation via AirPlay - see the iOS User Guide on your iPad3 (located in Safari Bookmarks Menu as iPad User Guide - look for Basics > Using AirPlay - the iPad3 with the latest iOS supports AirPlay mirroring as well.
5. There is an iOS app called Keynote Remote from Apple that allows you to remotely control your presentation from another iOS device such as an iPhone or iPad Touch but you need WiFi access to run it (there is a Bluetooth setup, but some have experienced difficulty using it)

Good Luck

I use my ipad3 to teach a bible class using a VGA adapter cord with the projector cord. I also use my iPod touch to remotely control the iPad using only Bluetooth and the keynote remote software. Works like a charm.

I have found preparing the presentation on the iPad using keynote and it's dictation function is a great time saver. I have bible software on the iPad, so copying & paste is very handy. Hope this helps anyone wondering if this really works!