Networked phone while traveling

Techn

Hi,

i'm thinking about going traveling following uni and am looking for a new phone i can use along the way to keep in touch via the internet

This is rather a broad topic about how much network prices will cost abroad, so i'll try and narrow things down.
Smart phones seem the way to go as they offer a wide range of connectivity (gprs, 3g, wifi.. etc). Plus i'm not bothered too much about making expensive calls, but would like to keep in contact via things like email, instant messaging, uploading to a blog, plus you can surely get skype apps and things like that?

However, i'm worried about how much data usage will cost me abroad, in places like spain, australia, nz and the US.
I've seen a few pay monthly plans on the htc phones (would love an iphone but far too expensive) that offer unlimited internet access, does this apply when using it abroad? (i'm guessing not).

If not a PAYG option seems likely, the htc wildfire looks good value for money in that respect. I'm sure hostels and the like will have wifi access which will be free (is with my ipod touch anyway), but do you think it will become expensive to use GPS and 3G for browsing, using maps and messaging?

Sorry about the long winded post,
thanks for any info you can provide

Techn

will browsing and messaging be expensive?