If my employer offers a workshare program during this recession and I own a small side business (even if it makes little or no income), am I ineligible for the workshare program?
Assuming you are paying into and eligible to collect regular Employment Insurance benefits for the job in question, I don't see how owning a side business would, by itself, affect your ability to participate in the workshare program. Many people own dormant businesses ($0 revenue / $0 income), or businesses with insignificant net income (e.g. a small table at the flea market, or a fledgling web-site with up-front costs and no ad revenue, yet ;-)
I think what matters is if your side business generated income substantial enough to put you over a certain threshold. Then you may be required to repay a portion of the EI benefits received through the workshare program. On this issue, I found the following article informative: How to make work-sharing work for you, from the Globe & Mail's Report on Business site. Here's a relevant quote:
"[...] If you work elsewhere during the agreement, and earn more than an amount equal to 40% of your weekly benefit rate, that amount shall be deducted from your work sharing benefits payable that week. [...]"
The definitive source for information on the workshare program is the Service Canada web site. In particular, see the Work-Sharing Applicant Guide, which discusses eligibility criteria. Section IV confirms the Globe article's statement above:
"[...] Earnings received in any week by a Work-Sharing participant, from sources other than Work-Sharing employment, that are in excess of an amount equal to 40% or $75 (whichever is greater) of the participant's weekly benefit rate, shall be deducted from the Work-Sharing benefits payable in that week. [...]"
Finally, here's one more interesting article that discusses the workshare program: Canada: Employment Law @ Gowlings - March 30, 2009.