This year the State of Maryland is going to make all Maryland property owners re-apply for their Homestead Deduction.
Property owners who use a residence as their Principle Residence will be receiving (starting Jan 1, 2008) their property tax assessments for 2008. The envelope will contain the standard Tax Assessment Notice as well as 2 additional pages.
These pages are NOT JUNK - I am sure many folks will miss this and toss these pages in the trash.
One page is informs property owners that everyone must re-apply for the Homestead Tax Deduction and the the other page is the actual application.
Property Owners will have the ability to mail in the paper application or apply online. The deadline is 4/1/08. 
You can read more on their website: State of Maryland Tax Credit
Make sure not to miss the deadline; as I am sure correcting after the fact won't be an easy task...
Search for Homes in Washington DC DC Real Estate News
Call James for all your Real Estate needs and questions; servicing Washington DC, Maryland and Virginia.
James,
I just heard about this yesterday. I do not have to deal with this as I was reassessed in 07. But I will have to do this in 2010.
I can't believe the lack of urgency and effort the state made in getting this info out. Because of this, it is my understanding that they extended the deadline until the end of May so there is still time. For those miss the new deadline, you can still re-apply but you won't receive the exemption on your next tax bill.
You can do it online or mail in your application.
Online: https://sdathtc.resiusa.org/homestead/
Mail In: http://www.dat.state.md.us/sdatweb/Homestead_application.pdf
Where are these deadlines actually stated? Especially the April 1st deadline?