Wireless b-g-a

The Intel 2915 Internal PRO/Wireless card (802.11 a/b/g, 54Mbps) that goes in the 9300 Inspiron laptop and probably others, has protocols b,g and now 'a', which I assume is the newest, fastest communication setup.

 

What is 'a', something like 5.8 GHz on cordless phones?  What advantages does it have?

 

I've read of people connecting to it in public facilities.  Does it have a place in the home?

 

And practically, WHEN are wireless routers going to support it?  The popular Linksys wireless broadband router WRT54g supports b and g, but not a.  Should I wait for WRT54ga since the 2915 already has support for 'a' built-in to the laptop?

 

Lastly, what is 'speedboost' or whatever on the WRT54gS?