Just wanted to say - I am accessing, tho mostly afk, SL 24 hours a day at the moment. I am testing a new app for my Googlephone - which is an Android based system.
The app- "Mobile Grid" allows me to chat or IM. I also know which of my friends are inworld, I can see myself on a sim map and can tell if there are any avies near to me. There are advantages and disadvantages - I also have access to group IM's - so can take part in debates while in a rl coffee shop or on a break in work - I can IM friends (had a convo with a new friend, Milarien Silverspar today - which I feel would have been previously unusual as she is in a very different timezone than me and even though it was my lunchtime - it was nearing midnight for her).
The main disadvantage is that because of the lack of presence of an avie, the "talking" is much more like phone messaging - though like Google Talk or phone MSN apps, is instant. The presence of avies, movement and "space" definately sets SL apart. Other disadvantages are that I cannot receive notices or notecards (though a message tells me if I do - but I cannot access them until I log in on my laptop) and people can see me in SL, but I can't see them - so threats of "weird" photos can be made by people like Aeris Betsen! :)
I am impressed by the app - access to SL is usually good as the 3G network is definately getting better.