I am not sure why anyone would say you need a different application for jpegs..... If I was shooting my Canon 5 D mark 2 in the mode where it fires off one raw, and one jpeg each time I pull the trigger.....the difference in Lightroom ( or any other program) would be that the jpeg may have some processing applied by the camera itself, whereas the Raw file will be flat....and need more tweaking than the jpeg will with things like saturation, sharpness, etc....But tweaking is still going to be required 99% of the time, so the tools used are pretty much the same....
The new Lightroom( I use the Creative Cloud Version--always 100% newest updates) does a great deal of what Photoshop used to be needed for....and the interface is drastically faster to work with for the rapid tweaking of a photo.
This Creative Cloud concept is pretty cool.....I am paying $29 per month, to get use of 100% of all the Adobe products....that includes Lightroom, Photoshop, Illustrator, Fireworks, Premier, Dreamweaver( awesome web page creation program), and more than a dozen others....and I am allowed to have these programs on 2 computers.
If you only wanted Lightroom, it is more like $10 per month. But anyone with multiple creative needs, can benefit greatly with the overall deal. If you are buying programs outright( the traditional model) , then in 6 months to a year, when they upgrade the program, suddenly you have to spend more money...to get the latest and greatest features....over several years, this can actually cost quite a bit of money.....With the Creative Cloud concept, you are always running the newest version, and the cost monthly is affordable and painless.