Wow!
I've read the long line of posts on this subject. It was interesting getting everyone's take on gmail.
For my part, as soon as someone invited me I jumped on the gmail bandwagon and never looked back.
If you've read this thread then you've seen PG's info on what gmail has to offer. I will, however, add my comment on 1GB of space and the search capability. With 1GB I am not worried about signing up for every email list for which I have the remotest interest - and I have a lot of interests. The 1GB coupled with the search ability puts me pretty much in heaven.
My philosophy, which permeates my life both professional and private, is that if you have the data then you can look at it; if you don't have the data you can not look at it. You can not predict the future value of data. You can predict that if you don't save data then you will need it in the future in a most desperate way. Folks at work (I am a developer) that think my ideas are silly invariably come asking for that email they deleted a while back, or for that source file that I backed up from the mainframe to my pc, or for the system logs that I backed up so they can do the trend analysis, etc.
Now....if you don't have space then you don't have space. But, if you do have space (and especially a really good search engine) then it is silly not to save the data.
That said - I currently have 5 invites for gmail.