On PGO there been discussions about startup time of applications,e.g. here.
The people on #gmpc will know I have been saying this for years. Nothing is as annoying as having to wait for a program to start up and splashscreens are stupid. GMPC will do a cold start in 230 ms (on my work laptop with a normal hdd) and a warm start off 199ms, it is directly ready to use. Though this can be tricky and YMMV (esp. opening and checking the sqlite database seems to take different times on different machines)
Also with stuffkeeper I have been working hard to keep the startup times short (opening the SQL database is however taking up a lot of time) and is still significantly shorter then 1 second.
But I am happy they are finally looking at this. Boot times are often not that important, people only do that once a day, or in my case once every X weeks. (I either leave it on, or put it in standby). However applications you are using constantly, closing and opening it. It is one of the biggest things annoying me when using f.e. thunderbird or firefox. If I open it, I have to wait seconds before I can use it.
I cannot wait for the future, I really like gnome3 (although because of memory constraints I switched back to openbox for now, gnome3 gets terribly slow if you have programs running using up all your 4gig of memory) and if they can speed up general usage it would be only better.