Hi mich21,
I am also in inland process and I sent on March. They are still processing visa extensions received up to March 10, 2009,
so as you said you applied on April you will wait about 104 days to get an answer. They also delayed to give my visa extension
and I got about one month and a half with no status, they say that you have a implied status when you are applying for Permanent Resident through a sponsor in Canada, this means that your wife won't be an illegal in Canada until receive visa extension answer. They usually grants more 6 months on visitor visa and the current time for receive a first answer about
the sponsorship is 5-6 months, so in August we will get some news.
You should call CIC to get your client ID number, and also ask about the visa extensions.
phone number: 1 888 242‑2100
To verify how long it may take to process your case:
http://www.cic.gc.ca/english/information/times/canada/process-in.aspgood luck with your application.
all the best!