Seems like more websites (particularly aesthetic ones) use web font embedding.

Google, appears to be serving these fonts.

What are your thoughts on using them?

<?php if($heartrate > 100) {die('this rant is gaining too much life of its own');} ?> :)

does not work right in more than half of user browsers, using windows and IE <=8, browser fault not code fault, so it isnt good to rely on it
requires a larger page download, depends on a third party server, so isnt good to rely on it
other thoughts
will be very interesting when more users use IE >=9 (ff chrome opera apple products, support most, if not identically, but few users actually use them) already have the fonts downloaded in the browser cache, and have the appararent immediate font support
google is better than hosting the same font yourself, the file will mostly be in the cache once a few designers start using it, even though the third party {everything} police (dot the t cross the eye anal retentive *expletive deleted*) already made laws trying to regulate everything to when I sit and
this rant is gaining too much life of its own

I think given time, computer centuries => 6months, the latest versions already have worked around IE differences, there will be few sites that dont have some font speciality
but wouldnt it be great if all the browsers declared the font the same way, (like ff does, not like safari & IE, blank spaces )

I'm using Google Webfonts myself, but it's too bad that not all browsers know how to work with custom fonts :(.

commented: thanks for the tip - I've been messing with a DIY solution +13

I heard that IE support embedded font sice IE6. Isn't right ? :)

add it to all the other things that ie does well? (short list)
as well as ie does anything == no
not fully dependable as written, google font api approaches reliable
I think, personal opinion only no reasons for it, that it will be the next big thing in a few computer centuries (6 month) as soon as mainstream developers discover the google api works almost properly in ie

What are the alternatives to webfonts? Cufon and Sifr? Which offers the best compatibility right now?

I looked into using embedded fonts only last week. Using the @font-face declaration at the top of my stylesheet, the font displayed successfully in all major browsers, including IE6+.

I abandoned the idea in the end, because the TTF file was rather large and substantially slowed the page loading. Still, it's a good, JS free option to consider for the future.

Yeah I think google are fairly reliable as web-font hosts. Unless somewhere down the line something terrible happens.

In any you would use this in a .css file and have a backup font

font-family: 'GoogleWebFont', Arial;

I guess it is a nice way to ensure good aliasing as well.