Not without using some sort of third party app.
The iPad can natively view quite a few different document formats, but not Microsoft PowerPoint presentations.
There are a few options should you need to view or edit this kind of document on your iPad:
Keynote is part of Apple’s own iWork suite of office applications. Many users swear by the desktop version and the view is that it’s certainly better than the Mac version of PowerPoint. The iPad version of Keynote has less features, and more compatibility issues with PowerPoint than the desktop version has.
Still, if you’re more about creating presentations then viewing them on your iPad then it’s an option for you.
Documents To Go
Documents To Go has been around for a while on various different devices. The iPad and iPhone version allows you to create, edit or view most Microsoft Office files.
You can also sync your created documents with any number of online file syncing services such as Google Docs, Dropbox, iDisk, Box.net and SugarSync.
There’s also a desktop application which offers syncing between your desktop documents and the ones on your iOS device, meaning you can start a document at work, save it and then continue working on it from your phone or iPad.
Splashtop Remote Desktop
As the name suggests, this isn’t an office suite as such. Instead it allows you to connect to a desktop PC (Windows or Mac) over a network or the Internet.
In doing this, you can view, edit and create pretty much any file you want on your iPad, as well as do countless other things.
The disadvantage to this is that you require a PC and an Internet connection for your iPad whenever you want to work on your PowerPoint documents. However, it’s the only way to get a full version of Microsoft PowerPoint on your iOS device.